Make cargo.features a crate-level config

[alibektas]

workspace
|-crate1
|-crate2
|-crate3
|_crate4

crate 2 and 4 have a feature called "example_feature" that i want to enable for RA,
so using a workspace setting is a no go, because RA will complain that crates 1 and 3 don't have this feature
creating rust-analyzer.toml in crate 2 and 4's root and adding cargo.features = ["example_feature"] has no effect,
however if i replace it with rust-analyzer.cargo.features = ["example_feature"], RA will complain that this is an invalid key that doesn't exist. So it reads the file but when it reads a correct key it doesn't apply that? I have no machine-wide or workspace or user overrides (using VSC right now but same happens in Vim).

Originally posted by @vaqxai in #13529 (comment)

What the title indicates is just a way to resolve this issue although making such a change is not wanted. This issue is just to discuss and shed a light on what we can do

[alibektas]

crate 2 and 4 have a feature called "example_feature" that i want to enable for RA,
so using a workspace setting is a no go,

@vaqxai I cannot reproduce any errors when I use cargo {build,check,metadata} --features example_feature. These are the three subcommands we use in rust-analyzer. Would you mind sharing your whole workspace ( I mean to say a minimal example where the said error is to be seen)?