bug(pip): pip in Windows is now called via py

[gnikit]

Instead of the incorrect python3

[codecov]

Codecov Report

Merging #822 (5138827) into main (3a6b8e4) will increase coverage by 0.02%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##             main     #822      +/-   ##
==========================================
+ Coverage   82.82%   82.84%   +0.02%     
==========================================
  Files          12       12              
  Lines        2276     2279       +3     
  Branches      201      205       +4     
==========================================
+ Hits         1885     1888       +3     
  Misses        384      384              
  Partials        7        7              

Impacted Files	Coverage Δ
src/lib/tools.ts	78.97% <75.00%> (-0.12%)	⬇️
src/lsp/client.ts	66.41% <0.00%> (+0.25%)	⬆️

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[gnikit]

To get the install location of the Python binaries (in case the application is not stored in the PATH)

python -c "import os, sysconfig;user_scripts_path = sysconfig.get_path('scripts', f'{os.name}_user');print(user_scripts_path)"

I think the extension should:

• try to install fortls (or any python package) using pip with user permissions except raise an error
• Check that it can be launched (i.e. pip install location is in PATH) if successful return True or undefined else run the above command to get the install location of the script, return the string.
• On the receiving end, make sure to cache the location to avoid unnecessary execution of the python prompt.

[gnikit]

Superseded by #824