Bye bye as command mut

[Shourya742]

This PR adds streaming capabilities to BootstrapCommand and migrate existing command streaming scenario's used in bootstrap.

r? @Kobzol

[rust-log-analyzer]

The job mingw-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] build_helper test:false 0.685
error: variables can be used directly in the `format!` string
   --> src/bootstrap/src/utils/exec.rs:657:27
    |
657 |                 Err(e) => panic!("failed to execute command: {:?}\nERROR: {e}", command),
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
    = note: `-D clippy::uninlined-format-args` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::uninlined_format_args)]`
help: change this to
    |
657 -                 Err(e) => panic!("failed to execute command: {:?}\nERROR: {e}", command),
657 +                 Err(e) => panic!("failed to execute command: {command:?}\nERROR: {e}"),
    |

[RUSTC-TIMING] bootstrap test:false 9.444
error: could not compile `bootstrap` (lib) due to 1 previous error
Build completed unsuccessfully in 0:09:56

[Kobzol]

Thanks! Left a few comments.

[Kobzol]

Maybe StreamingCommand? To keep it consistent with DeferredCommand.

[Kobzol]

We should explicitly panic here and let the user know that stream cannot be combined with caching and that they should use do_not_cache. Actually, it would be even better if stream was a method on BoostrapCommand, that would disable caching and return the streaming command directly, rather than going through DeferredCommand.

[Kobzol]

let Some(mut streaming_command) = streaming_command else { return true; };

[Kobzol]

This is good enough for now, but for profiling we'll want to have a unified way of finishing even the streaming commands in the execution context. But for now we can keep it like this.