feat(ivy): introduce concrete types for paths in ngtsc (#28523)

This commit introduces a new ngtsc sub-library, 'path', which contains
branded string types for the different kind of paths that ngtsc manipulates.
Having static types for these paths will reduce the number of path-related
bugs (especially on Windows) and will eliminate unnecessary defensive
normalizing.

See the README.md file for more detail.

PR Close #28523

packages/compiler-cli/src/ngtsc/path/test/logical_spec.ts

@@ -0,0 +1,53 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {LogicalFileSystem, LogicalProjectPath} from '../src/logical';
+import {AbsoluteFsPath} from '../src/types';
+
+describe('logical paths', () => {
+  describe('LogicalFileSystem', () => {
+    it('should determine logical paths in a single root file system', () => {
+      const fs = new LogicalFileSystem([abs('/test')]);
+      expect(fs.logicalPathOfFile(abs('/test/foo/foo.ts')))
+          .toEqual('/foo/foo' as LogicalProjectPath);
+      expect(fs.logicalPathOfFile(abs('/test/bar/bar.ts')))
+          .toEqual('/bar/bar' as LogicalProjectPath);
+      expect(fs.logicalPathOfFile(abs('/not-test/bar.ts'))).toBeNull();
+    });
+
+    it('should determine logical paths in a multi-root file system', () => {
+      const fs = new LogicalFileSystem([abs('/test/foo'), abs('/test/bar')]);
+      expect(fs.logicalPathOfFile(abs('/test/foo/foo.ts'))).toEqual('/foo' as LogicalProjectPath);
+      expect(fs.logicalPathOfFile(abs('/test/bar/bar.ts'))).toEqual('/bar' as LogicalProjectPath);
+    });
+
+    it('should continue to work when one root is a child of another', () => {
+      const fs = new LogicalFileSystem([abs('/test'), abs('/test/dist')]);
+      expect(fs.logicalPathOfFile(abs('/test/foo.ts'))).toEqual('/foo' as LogicalProjectPath);
+      expect(fs.logicalPathOfFile(abs('/test/dist/foo.ts'))).toEqual('/foo' as LogicalProjectPath);
+    });
+  });
+
+  describe('utilities', () => {
+    it('should give a relative path between two adjacent logical files', () => {
+      const res = LogicalProjectPath.relativePathBetween(
+          '/foo' as LogicalProjectPath, '/bar' as LogicalProjectPath);
+      expect(res).toEqual('./bar');
+    });
+
+    it('should give a relative path between two non-adjacent logical files', () => {
+      const res = LogicalProjectPath.relativePathBetween(
+          '/foo/index' as LogicalProjectPath, '/bar/index' as LogicalProjectPath);
+      expect(res).toEqual('../bar/index');
+    });
+  });
+});
+
+function abs(file: string): AbsoluteFsPath {
+  return AbsoluteFsPath.from(file);
+}