Improved and colorized help output + code quality improvements.

[kindermannhubert]

Before:

After:

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 77.43902% with 37 lines in your changes are missing coverage. Please review.

Project coverage is 77.3%. Comparing base (51230d1) to head (9746e7f).

Files	Patch %	Lines
CSharpRepl.Services/Theming/ThemeColor.cs	0.0%	6 Missing and 3 partials :warning:
CSharpRepl.Services/Nuget/NugetPackageInstaller.cs	33.3%	5 Missing and 1 partial :warning:
CSharpRepl.Services/Nuget/NugetHelper.cs	33.3%	3 Missing and 1 partial :warning:
CSharpRepl/ReadEvalPrintLoop.cs	90.2%	0 Missing and 4 partials :warning:
...rpRepl.Services/Roslyn/RoslynServices.Overloads.cs	33.3%	2 Missing :warning:
CSharpRepl.Services/Roslyn/RoslynServices.cs	33.3%	2 Missing :warning:
CSharpRepl/CommandLine.cs	92.5%	2 Missing :warning:
CSharpRepl.Services/Disassembly/Disassembler.cs	85.7%	0 Missing and 1 partial :warning:
...Repl.Services/Roslyn/Formatting/FormattedObject.cs	0.0%	0 Missing and 1 partial :warning:
.../MetadataResolvers/AlternativeReferenceResolver.cs	50.0%	1 Missing :warning:
... and 5 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #338 +/- ## ======================================= - Coverage 77.6% 77.3% -0.4% ======================================= Files 83 83 Lines 5600 5607 +7 Branches 730 736 +6 ======================================= - Hits 4347 4335 -12 - Misses 986 998 +12 - Partials 267 274 +7 ```

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