chore: separate tslint config files for build and vscode

This is a follow-up to #964.

Two config files are in place now:
- tslint.build.json for CLI build scripts
- tslint.json for vscode

packages/cli/generators/project/templates/tslint.build.json

@@ -1,17 +1,4 @@
 {
   "$schema": "http://json.schemastore.org/tslint",
-  "extends": ["./tslint.json"],
-  // This configuration files enabled rules which require type checking
-  // and therefore cannot be run by Visual Studio Code TSLint extension
-  // See https://github.com/Microsoft/vscode-tslint/issues/70
-  "rules": {
-    // These rules find errors related to TypeScript features.
-
-    // These rules catch common errors in JS programming or otherwise
-    // confusing constructs that are prone to producing bugs.
-
-    "await-promise": true,
-    "no-floating-promises": true,
-    "no-void-expression": [true, "ignore-arrow-function-shorthand"]
-  }
+  "extends": ["./node_modules/@loopback/build/config/tslint.build.json"]
 }

packages/cli/generators/project/templates/tslint.json

@@ -1,7 +1,7 @@
 {
   "$schema": "http://json.schemastore.org/tslint",
 <% if (project.loopbackBuild) { -%>
-  "extends": ["./node_modules/@loopback/build/config/tslint.build.json"]
+  "extends": ["./node_modules/@loopback/build/config/tslint.common.json"]
 <% } else { -%>
   // See https://palantir.github.io/tslint/rules/
   "rules": {

tslint.build.json

@@ -1,20 +1,10 @@
 {
   "$schema": "http://json.schemastore.org/tslint",
-  "extends": [
-    "./tslint.json"
-  ],
-  // This configuration files enabled rules which require type checking
-  // and therefore cannot be run by Visual Studio Code TSLint extension
-  // See https://github.com/Microsoft/vscode-tslint/issues/70
-  "rules": {
-    // These rules find errors related to TypeScript features.
-
-
-    // These rules catch common errors in JS programming or otherwise
-    // confusing constructs that are prone to producing bugs.
-
-    "await-promise": true,
-    "no-floating-promises": true,
-    "no-void-expression": [true, "ignore-arrow-function-shorthand"]
+  "extends": ["./packages/build/config/tslint.build.json"],
+  "linterOptions": {
+    "exclude": [
+      "./packages/cli/generators/*/templates/**/*",
+      "./packages/cli/test/sandbox/**/*"
+    ]
   }
 }

tslint.json

@@ -1,6 +1,6 @@
 {
   "$schema": "http://json.schemastore.org/tslint",
-  "extends": ["./packages/build/config/tslint.build.json"],
+  "extends": ["./packages/build/config/tslint.common.json"],
   "linterOptions": {
     "exclude": [
       "./packages/cli/generators/*/templates/**/*",