Update plugin restore caching:

- support setting cache dir via env var
- updated default gh-action to cache plugins

.github/workflows/default.yml

@@ -14,6 +14,7 @@ on:
 env:
   DOTNET_NOLOGO: true
   NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
+  PLUGIN_SDK_CACHE: ${{ github.workspace }}/.plugins/cache
 
 jobs:
   build:
@@ -29,6 +30,14 @@ jobs:
           cache-dependency-path: ./**/packages.lock.json
           global-json-file: global.json
 
+      - name: cache plugins
+        uses: actions/cache@v3
+        with:
+          key: plugin-cache-${{ runner.os }}-${{ hashFiles('**/plugins.lock.json') }}
+          path: ${{ env.PLUGIN_SDK_CACHE }}
+          restore-keys: |
+            plugin-cache-${{ runner.os }}-
+
       - name: restore
         run: dotnet restore --locked-mode
 
@@ -53,7 +62,7 @@ jobs:
           global-json-file: global.json
 
       - name: restore
-        run: dotnet restore --locked-mode
+        run: dotnet restore src/LethalCompany.Plugin.Sdk.csproj --locked-mode
 
       - name: pack
         run: dotnet pack src/LethalCompany.Plugin.Sdk.csproj -c Release -o .sdk --no-restore

src/Sdk/Sdk.targets

@@ -17,6 +17,7 @@
     <PluginManagerDataDir Condition=" '$(PluginManagerDataDir)' == '' AND '$(PluginManager)' == 'r2modman' ">$(AppData)\r2modmanPlus-local\LethalCompany\</PluginManagerDataDir>
     <PluginManagerDataDir Condition=" '$(PluginManagerDataDir)' == '' ">$(AppData)\Thunderstore Mod Manager\DataFolder\LethalCompany\</PluginManagerDataDir>
 
+    <PluginCacheDir Condition=" '$(PluginCacheDir)' == '' AND '$(PLUGIN_SDK_CACHE)' != '' ">$([MSBuild]::EnsureTrailingSlash($(PLUGIN_SDK_CACHE)))</PluginCacheDir>
     <PluginCacheDir Condition=" '$(PluginCacheDir)' == '' ">$(PluginManagerDataDir)cache\</PluginCacheDir>
     <PluginProfileDir Condition=" '$(PluginStagingProfile)' != '' AND '$(PluginProfileDir)' == '' AND '$(PluginManagerDataDir)' != '' ">$(PluginManagerDataDir)\profiles\$(PluginStagingProfile)\</PluginProfileDir>