Rollup merge of #139978 - Kobzol:ci-test-summary, r=jieyouxu

Add citool command for generating a test dashboard

This PR implements an initial version of a test suite dashboard, which shows which tests were executed on CI and which tests were ignored. This was discussed [here](https://rust-lang.zulipchat.com/#narrow/channel/238009-t-compiler.2Fmeetings/topic/.5Bsteering.5D.202025-04-11.20Dealing.20with.20disabled.20tests/with/512799036). The dashboard is still quite bare-bones, but I think that it could already be useful.

The next step is to create a job index, similarly to the post-merge report, and link from the individual tests to the job that executed them.

You can try it locally like this:
```bash
$ cargo run --manifest-path src/ci/citool/Cargo.toml --release \
    -- test-dashboard 38c560ae681d5c0d3fd615eaedc537a282fb1086 --output-dir dashboard
```
and then open `dashboard/index.html` in a web browser.

CC ````@wesleywiser````

r? ````@jieyouxu````

Author: ChrisDenton