refactor(ngcc): clean up unused imports, unused regex parenthesis, typos

This is a follow-up to angular#37075, because I didn't manage to finish my
review before the PR got merged.

packages/compiler-cli/ngcc/src/dependencies/esm_dependency_host.ts

@@ -225,7 +225,7 @@ export class EsmDependencyHost extends DependencyHostBase {
  * in this file, true otherwise.
  */
 export function hasImportOrReexportStatements(source: string): boolean {
-  return /(?:import|export)[\s\S]+?(["'])(?:(?:\\\1|.)*?)\1/.test(source);
+  return /(?:import|export)[\s\S]+?(["'])(?:\\\1|.)+?\1/.test(source);
 }
 
 
@@ -261,4 +261,4 @@ function canPrecedeARegex(kind: ts.SyntaxKind): boolean {
     default:
       return true;
   }
-}
+}

packages/compiler-cli/ngcc/src/entry_point_finder/targeted_entry_point_finder.ts

@@ -5,18 +5,15 @@
  * 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 {AbsoluteFsPath, FileSystem, join, PathSegment, relative, relativeFrom} from '../../../src/ngtsc/file_system';
-import {EntryPointWithDependencies} from '../dependencies/dependency_host';
+import {AbsoluteFsPath, FileSystem} from '../../../src/ngtsc/file_system';
 import {DependencyResolver, SortedEntryPointsInfo} from '../dependencies/dependency_resolver';
 import {Logger} from '../logging/logger';
 import {hasBeenProcessed} from '../packages/build_marker';
 import {NgccConfiguration} from '../packages/configuration';
-import {EntryPoint, EntryPointJsonProperty, getEntryPointInfo, INCOMPATIBLE_ENTRY_POINT, NO_ENTRY_POINT} from '../packages/entry_point';
+import {EntryPointJsonProperty} from '../packages/entry_point';
 import {PathMappings} from '../path_mappings';
 
-import {EntryPointFinder} from './interface';
 import {TracingEntryPointFinder} from './tracing_entry_point_finder';
-import {getBasePaths} from './utils';
 
 /**
  * An EntryPointFinder that starts from a target entry-point and only finds

packages/compiler-cli/ngcc/src/entry_point_finder/tracing_entry_point_finder.ts

@@ -24,7 +24,7 @@ import {getBasePaths} from './utils';
  * This is faster than searching the entire file-system for all the entry-points,
  * and is used primarily by the CLI integration.
  *
- * There are two concrete implementation of this class.
+ * There are two concrete implementations of this class.
  *
  * * `TargetEntryPointFinder` - is given a single entry-point as the initial entry-point
  * * `ProgramBasedEntryPointFinder` - computes the initial entry-points from program files given by