Add basic C++ path mapping support

Basic support for path mapping for `CppCompile` actions is added by wiring up `PathMapper` with:
* structured path variables for files and include paths (`Artifact` and `NestedSet<PathFragment>`)
* inputs/outputs via `Spawn#getPathMapper()`
* header discovery

Also turns `external_include_paths` into a structured variable, which was missed in #22463.

The following features are known to be unsupported for now:
* `layering_check` (requires rewriting paths to and in module maps)
* source tree artifacts (requires wiring up `PathMapper` in `CppCompileActionTemplate`)
* location expanded paths to generated files such as sanitizer suppression lists (requires heuristically rewriting paths in `user_compile_flags`)

These limitations will be lifted in follow-up PRs.

Work towards #6526

RELNOTES: Experimental support for path mapping `CppCompile` actions can be enabled via `--modify_execution_info=CppCompile=+supports-path-mapping`.

Closes #22445.

PiperOrigin-RevId: 646109274
Change-Id: I6f4eb92b6be3052547f144c681b6588e9fc40693

src/main/java/com/google/devtools/build/lib/actions/SimpleSpawn.java

@@ -41,6 +41,7 @@ public final class SimpleSpawn implements Spawn {
   private final ImmutableList<ActionInput> outputs;
   // If null, all outputs are mandatory.
   @Nullable private final Set<? extends ActionInput> mandatoryOutputs;
+  private final PathMapper pathMapper;
   private final LocalResourcesSupplier localResourcesSupplier;
   private ResourceSet localResourcesCached;
 
@@ -55,7 +56,8 @@ private SimpleSpawn(
       Collection<? extends ActionInput> outputs,
       @Nullable final Set<? extends ActionInput> mandatoryOutputs,
       @Nullable ResourceSet localResources,
-      @Nullable LocalResourcesSupplier localResourcesSupplier) {
+      @Nullable LocalResourcesSupplier localResourcesSupplier,
+      PathMapper pathMapper) {
     this.owner = Preconditions.checkNotNull(owner);
     this.arguments = Preconditions.checkNotNull(arguments);
     this.environment = Preconditions.checkNotNull(environment);
@@ -77,6 +79,7 @@ private SimpleSpawn(
       this.localResourcesSupplier = localResourcesSupplier;
       this.localResourcesCached = null;
     }
+    this.pathMapper = pathMapper;
   }
 
   public SimpleSpawn(
@@ -101,7 +104,8 @@ public SimpleSpawn(
         outputs,
         mandatoryOutputs,
         localResources,
-        /*localResourcesSupplier=*/ null);
+        /* localResourcesSupplier= */ null,
+        PathMapper.NOOP);
   }
 
   @SuppressWarnings("TooManyParameters")
@@ -126,8 +130,63 @@ public SimpleSpawn(
         tools,
         outputs,
         mandatoryOutputs,
-        /*localResources=*/ null,
-        localResourcesSupplier);
+        /* localResources= */ null,
+        localResourcesSupplier,
+        PathMapper.NOOP);
+  }
+
+  public SimpleSpawn(
+      ActionExecutionMetadata owner,
+      ImmutableList<String> arguments,
+      ImmutableMap<String, String> environment,
+      ImmutableMap<String, String> executionInfo,
+      ImmutableMap<Artifact, ImmutableList<FilesetOutputSymlink>> filesetMappings,
+      NestedSet<? extends ActionInput> inputs,
+      NestedSet<? extends ActionInput> tools,
+      Collection<? extends ActionInput> outputs,
+      @Nullable Set<? extends ActionInput> mandatoryOutputs,
+      LocalResourcesSupplier localResourcesSupplier,
+      PathMapper pathMapper) {
+    this(
+        owner,
+        arguments,
+        environment,
+        executionInfo,
+        filesetMappings,
+        inputs,
+        tools,
+        outputs,
+        mandatoryOutputs,
+        null,
+        localResourcesSupplier,
+        pathMapper);
+  }
+
+  public SimpleSpawn(
+      ActionExecutionMetadata owner,
+      ImmutableList<String> arguments,
+      ImmutableMap<String, String> environment,
+      ImmutableMap<String, String> executionInfo,
+      ImmutableMap<Artifact, ImmutableList<FilesetOutputSymlink>> filesetMappings,
+      NestedSet<? extends ActionInput> inputs,
+      NestedSet<? extends ActionInput> tools,
+      Collection<? extends ActionInput> outputs,
+      @Nullable Set<? extends ActionInput> mandatoryOutputs,
+      ResourceSet localResources,
+      PathMapper pathMapper) {
+    this(
+        owner,
+        arguments,
+        environment,
+        executionInfo,
+        filesetMappings,
+        inputs,
+        tools,
+        outputs,
+        mandatoryOutputs,
+        localResources,
+        null,
+        pathMapper);
   }
 
   public SimpleSpawn(
@@ -226,6 +285,11 @@ public ResourceSet getLocalResources() throws ExecException {
     return localResourcesCached;
   }
 
+  @Override
+  public PathMapper getPathMapper() {
+    return pathMapper;
+  }
+
   @Override
   public String getMnemonic() {
     return owner.getMnemonic();

src/main/java/com/google/devtools/build/lib/rules/cpp/CcModule.java

@@ -27,6 +27,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.actions.PathMapper;
 import com.google.devtools.build.lib.analysis.AnalysisUtils;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.config.BuildConfigurationValue;
@@ -288,7 +289,7 @@ public Dict<String, String> getEnvironmentVariable(
     return Dict.immutableCopyOf(
         featureConfiguration
             .getFeatureConfiguration()
-            .getEnvironmentVariables(actionName, variables));
+            .getEnvironmentVariables(actionName, variables, PathMapper.NOOP));
   }
 
   @Override