autodetect shim path

[ca1e]

Description

autodetect shim path

Motivation and Context

change function get_shim_path() in core.ps1

How Has This Been Tested?

scoop config shim testbad
scoop rest * # should output the warning

scoop config shim 71
scoop rest * # should use '71' version

scoop config shim kiennq
scoop rest * # should use 'kiennq' version

scoop config shim default
scoop rest * # should use 'kiennq' version

scoop config rm shim
scoop rest * # should use 'kiennq' version

Checklist:

• [x] I have read the Contributing Guide.
• [x] I have ensured that I am targeting the develop branch.
• [ ] I have updated the documentation accordingly.
• [ ] I have updated the tests accordingly.
• [ ] I have added an entry in the CHANGELOG.