fix: Wrap rust-analyzer when rust-src is present

[eureka-cpu]

Closes #232

This wraps rust-analyzer by default if the toolchain contains the rust-src component, exporting RUST_SRC_PATH. This also adds the option to override the nightly rust-analyzer with rust-src from a toolchain.

[eureka-cpu]

Still need to test for the vs code extension and try it out in a few different terminal based editors.

[eureka-cpu]

Tested it out in the helix editor on linux, seems to work fine. Looks like I need to investigate some build failure on macos.

[eureka-cpu]

Okay, I think I just needed to patch the correct binary if it gets wrapped that actually changes, but linux is less picky.

Ah here's the culprit:

rust-analyzer-preview-nightly-complete> error: install_name_tool: changing install names or rpaths can't be redone for: /nix/store/n8dxsy2r4h1w9x79f2q89d6gdzzn49ci-rust-analyzer-preview-nightly-complete-2026-02-17/bin/.rust-analyzer-wrapped (for architecture arm64) because larger updated load commands do not fit (the program must be relinked, and you may need to use -headerpad or -headerpad_max_install_names)

[figsoda]

Sorry for not taking a look at the original issue earlier, but I don't think this is needed: #232 (comment)

[eureka-cpu]

Sorry for not taking a look at the original issue earlier, but I don't think this is needed: #232 (comment)

I replied there, but just for posterity I'm actually having the same issues even while using withComponents, but this wrapper does solve the issue for me.

The macos failure is actually on main as well, I just ran it locally on my M1.