feat(http-client-csharp): adopt TCGC getAllOperations

- update emitter logic to derive operation defintions from TCGC instead of raw compiler result
- update `ExampleMockValueBuilder` to get constant value from `InputLiteralType`
- add implicit conversion operation from `InputLiteralType` to `InputConstant`
- update unit test cases
- minor error message improvment

part of Azure/autorest.csharp#3994

packages/http-client-csharp/emitter/src/emitter.ts

@@ -135,7 +135,7 @@ export async function $onEmit(context: EmitContext<NetEmitterOptions>) {
         const existingProjectOption = options["existing-project-folder"]
           ? `--existing-project-folder ${options["existing-project-folder"]}`
           : "";
-        const debugFlag = options.debug ?? false ? " --debug" : "";
+        const debugFlag = (options.debug ?? false) ? " --debug" : "";
 
         const projectRoot = findProjectRoot(dirname(fileURLToPath(import.meta.url)));
         const generatorPath = resolvePath(