fix: Add -Zjson-target-spec on Cargo calls where needed

[ChayimFriedman2]

Fixes #21821.

CC @ShoyuVanilla assuming you know - do we need to gate this only for affected Cargo versions? If so, how?

[ShoyuVanilla]

Yeah, the older versions without that flag will error with it. For the later, I guess we could just do it based on the toolchain version. Would that be hard because of some quirks in our codebase? (I can't check whether it's hard or not since I'm outside rn. Sry 😅 )

[Veykril]

We already have the sysroot here so we should have the toolchain version queried already somewhere

[ShoyuVanilla]

As Lukas said we should the toolchain version available there, I guess you could compare the toolchain version like the following lines:

rust-analyzer/crates/project-model/src/cargo_config_file.rs

Lines 171 to 173 in 803fb51

	let usage = if *toolchain_version >= MINIMUM_TOOLCHAIN_VERSION_SUPPORTING_LOCKFILE_PATH_ENV {
	LockfileUsage::WithEnvVar
	} else if *toolchain_version >= MINIMUM_TOOLCHAIN_VERSION_SUPPORTING_LOCKFILE_PATH_FLAG {