Added remove unused imports assist
This resolves the most important part of #5131. I needed to make a couple of cosmetic changes to the search infrastructure to do this.
A few open questions:
* Should imports that don't resolve to anything be considered unused? I figured probably not, but it would be a trivial change to make if we want it.
* Is there a cleaner way to make the edits to the use list?
* Is there a cleaner way to get the list of uses that intersect the current selection?
* Is the performance acceptable? When testing this on itself, it takes a good couple seconds to perform the assist.
* Is there a way to hide the rustc diagnostics that overlap with this functionality?
internal: Defer structured snippet rendering to allow escaping snippet bits
Since we know exactly where snippets are, we can transparently escape snippet bits to the exact text edits that need it, and not have to do it for anything other text edits.
Also will eventually fix#11006 once all assists are migrated. This comes as a side-effect of text edits that don't have snippets get marked as having no insert formatting at all.
internal: Format let-else
As nightly finally got support for it I went ahead and formatted r-a with the latest nightly, then with the latest stable (in case other stuff changed)
Fix runnable detection for `#[tokio::test]`
fix#15141
It is hacky, and it wouldn't work for e.g. this case:
```Rust
use ::core::prelude;
#[prelude::v1::test]
fn foo() {
}
```
But it works for the tokio case. We should use the name resolution here somehow, and after that we should probably also get rid of the ast based `test_related_attribute` function.
internal: add `library` fixture meta
Currently, there is no way to specify `CrateOrigin` of a file fixture ([this] might be a bug?). This PR adds `library` meta to explicitly specify the fixture to be `CrateOrigin::Library` and also makes sure crates that belong to a library source root are set `CrateOrigin::Library`.
(`library` isn't really the best name. It essentially means that the crate is outside workspace but `non_workspace_member` feels a bit too long. Suggestions for the better name would be appreciated)
Additionally:
- documents the fixture meta syntax as thoroughly as possible
- refactors relevant code
[this]: 4b06d3c595/crates/base-db/src/fixture.rs (L450)
internal: Add run-tests command
This command is similar to `cargo test` except that it uses r-a to run tests instead of compiling and running them with rustc. This is slower than `cargo test` and it is only useful for me to see a bird view of what needs to be fixed. The current output is:
```
48 passed, 5028 failed, 2 ignored
All tests 174.74s, 648ginstr
```
48 is very low, but higher than what I originally thought.
Now that there is some passing tests, I can show the plan:
https://github.com/rust-lang/rust-analyzer/assets/45197576/76d7d777-1843-4ca4-b7fe-e463bdade6cb
That is, at the end, I want to be able to immediately re run every test after every change. (0.5s is not really immediate, but it's not finished yet, and it is way better than 8s that running a typical test in r-a will take on my system)
Added a test near positive extermes and two test near negative
extermes as well one for 0.
Added a test using the `as` cast and one with comparison with 0.
