fix(path): resolve symlink in Windows

[linrongbin16]

Thanks to your contribute, while please finish below tasks:

Regression Test

Platforms

• windows
• macOS
• linux

Tasks

• Use <leader>gl to copy git link.
• Use <leader>gL to open git link in browser.
• Copy git link in a symlink directory of git repo.
• Copy git link in an un-pushed git branch, and receive an expected error.
• Copy git link in a pushed git branch but edited file, and receive a warning says the git link could be wrong.

[codecov]

Codecov Report

Attention: 30 lines in your changes are missing coverage. Please review.

Files	Coverage Δ
lua/gitlinker/logger.lua	90.32% <100.00%> (-0.73%)	⬇️
lua/gitlinker/spawn.lua	78.90% <100.00%> (+0.33%)	⬆️
lua/gitlinker.lua	37.90% <0.00%> (ø)
lua/gitlinker/git.lua	10.79% <0.00%> (+0.65%)	⬆️
lua/gitlinker/util.lua	16.27% <11.53%> (+5.16%)	⬆️

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