Fix compiler bug with nested optional arguments

This commit fixes compiler bug where it fails when optional values are
compiled into absent values in nested calls.

- Throw exception with more context for easier future debugging.
- Add better validation of argument values for nested calls.
- Refactor `FunctionCallCompiler` for better clarity and modularize it
  to make it more maintainable and testable.
- Refactor related interface to not have `I` prefix, and
  function/variable names for better clarity.

Context:

Discovered this issue while attempting to call
`RunInlineCodeAsTrustedInstaller` which in turn invokes `RunPowerShell`
for issue #246. This led to the realization that despite parameters
flagged as optional, the nested argument compilation didn't support
them.

tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub.ts

@@ -5,7 +5,19 @@ import { FunctionCallArgumentStub } from './FunctionCallArgumentStub';
 export class FunctionCallArgumentCollectionStub implements IFunctionCallArgumentCollection {
   private args = new Array<IFunctionCallArgument>();
 
-  public withArgument(parameterName: string, argumentValue: string) {
+  public withEmptyArguments(): this {
+    this.args.length = 0;
+    return this;
+  }
+
+  public withSomeArguments(): this {
+    return this
+      .withArgument('firstTestParameterName', 'first-parameter-argument-value')
+      .withArgument('secondTestParameterName', 'second-parameter-argument-value')
+      .withArgument('thirdTestParameterName', 'third-parameter-argument-value');
+  }
+
+  public withArgument(parameterName: string, argumentValue: string): this {
     const arg = new FunctionCallArgumentStub()
       .withParameterName(parameterName)
       .withArgumentValue(argumentValue);
@@ -13,7 +25,7 @@ export class FunctionCallArgumentCollectionStub implements IFunctionCallArgument
     return this;
   }
 
-  public withArguments(args: { readonly [index: string]: string }) {
+  public withArguments(args: { readonly [index: string]: string }): this {
     for (const [name, value] of Object.entries(args)) {
       this.withArgument(name, value);
     }