Add fixes for target-shell prompt

[Miauwkeru]

There was an issue with the TargetCmd in the case the prompt was defined in the config file, yet didn't contain {cmd} or {base}. This fixes that issue

and some fixes for typing consistency

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 79.16%. Comparing base (bb9a488) to head (2a93fe1).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/target/tools/shell.py	40.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #943      +/-   ##
==========================================
- Coverage   79.17%   79.16%   -0.01%     
==========================================
  Files         344      344              
  Lines       30350    30352       +2     
==========================================
  Hits        24029    24029              
- Misses       6321     6323       +2     

Flag	Coverage Δ
unittests	79.16% <40.00%> (-0.01%)	⬇️

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[JSCU-CNI]

I believe it should return False. If a do_ or cmd_ function returns True it is a sign the Cli should exit.

[Miauwkeru]

aah, TIL. Will change it

[JSCU-CNI]

Kind of counter intuitive if you ask me, but that's how it works 😅. Perhaps it is inspired by 0 and 1 exit codes.

[Miauwkeru]

Yeah, it definitely feels counterintuitive. I guess its the exit code thing to make it feel like a shell where a non zero value gets treated as an error. Anyway, fixed!

Fixed