PR Summary

Previously we had to make workarounds in #6025 and #7631 to enable logging as early as possible.
A root of the problem is that command line parser has a dependency on ConsoleHost being initialized late.

Main change in the PR is to refactor CommandLineParameterParser and remove the dependency on ConsoleHost.
Now we create CommandLineParameterParser at startup as static and can run the parser immediately after pwsh launch. Later, after ConsoleHost is initialized, we write the parser's errors, banner and helps.

Now we call PSEtwLog.LogConsoleStartup() early in one place for both Unix and Windows.

While refactoring and testing the parser I discovered NRE in an edge case: pwsh -removeworkingdirectorytrailingcharacter throws NRE. As result I added #nullable enable in some files to make the code more reliable.

UnmanagedPSEntry.Start() uses still old signature. It was refactored too: new method create with removed unneeded parameters and old one was marked with Obsolete attribute.

CommandLineParameterParser.WriteCommandLineError() method was renamed to SetCommandLineError().

In CommandLineParameterParser.ParseHelper() was added fast return if pwsh started with no parameters (args.Length == 0).

Unused parameters was removed from the parser - iss, isswait and modules.

Waiting a debugger in remoting scenario was moved in WaitingRemoteDebugger() method that called later after ConsoleHost initialized.

CommandLineParameterParser.EarlyParse() was removed - now main parser is called in the place.

NullHostUserInterface was not fully refactored for nullable reference types because PSHostUserInterface base class must be refactored first. We can defer the work.

After the change that we can finally add xUnix tests in follow PR.

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