Refactor tsconfigs to share compiler options

This lets each config specify *only* how it actually does a build (or
not!), while sharing the config explicitly.

It also fixes an existing bug in the compilation settings which was not
affecting *normal* TS compilation with `tsc`, but was generating noise
in the `broccoli-typescript-compiler` pipeline because the packages
happened to be resolved in a different order such that the `loader`
"package" definition, and its declaration of the `require` module, was
not present in the graph. Set it explicitly in `compilerOptiosn.paths`
to fix that.

.gitattributes

@@ -1,2 +1,5 @@
 # Set the default behavior, in case people don't have core.autocrlf set.
-* text=auto
+* text=auto
+
+# Tell GH to render all tsconfigs in the tsconfig dir correctly.
+tsconfig/*.json linguist-language=JSON-with-Comments

tsconfig.json

@@ -1,39 +1,9 @@
 {
+  "extends": "./tsconfig/compiler-options.json",
   "compilerOptions": {
-    // Compilation Configuration
-    "target": "es2017",
-    "sourceMap": true,
     "outDir": "dist",
-    "baseUrl": "packages",
-    "rootDir": "packages",
-
-    // Environment Configuration
-    "experimentalDecorators": true,
-    "moduleResolution": "node",
-
-    // Enhance Strictness
-    "strict": true,
-    "noImplicitReturns": true,
-    "allowUnreachableCode": false,
-    "noPropertyAccessFromIndexSignature": true,
-    "noUnusedLocals": true,
-    "noUncheckedIndexedAccess": true,
-    "noUnusedParameters": true,
-    "esModuleInterop": false,
-    "allowSyntheticDefaultImports": false,
-
-    "newLine": "LF",
-    "noEmit": true,
-
-    "allowJs": true,
-    "checkJs": false,
-
-    "paths": {
-      "backburner": ["../node_modules/backburner.js/dist/backburner.d.ts"]
-    }
+    "noEmit": true
   },
-
   "include": ["packages/**/*.ts"],
-
   "exclude": ["dist", "node_modules", "tmp", "types"]
 }

tsconfig/compiler-options.json

@@ -0,0 +1,35 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "compilerOptions": {
+    // Compilation Configuration
+    "target": "es2019",
+    "sourceMap": true,
+    "baseUrl": "../packages",
+    "rootDir": "../packages",
+
+    // Environment Configuration
+    "experimentalDecorators": true,
+    "moduleResolution": "node",
+
+    // Enhance Strictness
+    "strict": true,
+    "noImplicitReturns": true,
+    "allowUnreachableCode": false,
+    "noPropertyAccessFromIndexSignature": true,
+    "noUnusedLocals": true,
+    "noUncheckedIndexedAccess": true,
+    "noUnusedParameters": true,
+    "esModuleInterop": false,
+    "allowSyntheticDefaultImports": false,
+
+    "newLine": "LF",
+
+    "allowJs": true,
+    "checkJs": false,
+
+    "paths": {
+      "backburner": ["../node_modules/backburner.js/dist/backburner.d.ts"],
+      "require": ["./loader/lib/index.d.ts"]
+    }
+  }
+}