Automate crate deployment

[Kobzol]

We have a bunch of repos under the rust-lang organization that are published as crates.io crates. Maintainers of such crates often go to Zulip to ask (infra, or other) people for publishing the crate.

It would be great if we could add GitHub CI workflow pipelines to said repositories to automate this process. The simplest way to do that is to crate a workflow that either publishes when a tag is pushed, or manually (through workflow_dispatch).

For now, we'll need an infra admin to manually configure a crates.io token for each repository.

Some repositories that I have encountered so far that had asked for a release recently:

• backtrace-rs
• libc
• libm
• cmake-rs
• rustc-hash
• spec
• rustc-demangle (Add a CI workflow to publish new releases after a tag is pushed rustc-demangle#71)
• compiler-builtins (Add release-plz for automatic releases. compiler-builtins#643)
• jobserver-rs (CI: Support automatic publish to crates.io on tag creation jobserver-rs#89)
• cargo (Add workflow to publish Cargo automatically cargo#14202)
• rustwide (CI: Add automatic publish on tag creation rustwide#88)
• cc-rs (CI: Add automatic publish on tag creation cc-rs#978)
• measureme (Add GitHub Workflow for publishing measureme measureme#221)