feat(cli): add __where_am_i command

[nhedger]

Summary

This PR adds a new hidden __where_am_i command that returns the path to the running executable.

I'm hoping this command will allow us to resolve the path to the actual binary when we're given the path to a shim instead.

Credits to @GongT for suggesting the idea.

Test Plan

• Running biome __where_am_i prints the path to the binary
• Running ./shim.sh __where_am_i prints the path to the original binary

[bijela-gora]

@nhedger

Thanks for this. Helped me to make the Biome VS Code extension work.

The issue was that the root node_modules dir is one level deeper then .git dir and for some reasons when I specified biome.lsp.bin as /js/node_modules/bin/biome that doesn't help.
After I run the pnpm exec biome __where_am_i it printed /home/username/Projects/the-project/js/node_modules/@biomejs/cli-linux-x64/biome and I set "biome.lsp.bin": "./js/node_modules/@biomejs/cli-linux-x64/biome", - that make the VS Code extension to work.

Thanks!