fix(linker/compiler): rename const to avoid duplicate declaration (#10457)

Currently in the `linker/compiler.ts` file, the **same identifier** is used in **two declarations**:
```typescript
export type CompilerOptions = { … }
…
export const CompilerOptions = new OpaqueToken('compilerOptions');
```
This breaks the API doc generation. I’m surprised that this was not flagged by the tsc.

The duplicate declaration was introduced in 46b212706b.

tools/public_api_guard/core/index.d.ts

@@ -258,13 +258,21 @@ export declare class Compiler {
     compileModuleSync<T>(moduleType: ConcreteType<T>): NgModuleFactory<T>;
 }
 
+/** @experimental */
+export declare const COMPILER_OPTIONS: OpaqueToken;
+
 /** @experimental */
 export declare abstract class CompilerFactory {
     abstract createCompiler(options?: CompilerOptions[]): Compiler;
 }
 
 /** @experimental */
-export declare const CompilerOptions: OpaqueToken;
+export declare type CompilerOptions = {
+    useDebug?: boolean;
+    useJit?: boolean;
+    defaultEncapsulation?: ViewEncapsulation;
+    providers?: any[];
+};
 
 /** @stable */
 export declare var Component: ComponentMetadataFactory;