* xtask: Add arguments to `publish`
that allow specifying a custom git remote to push to and a custom cargo
registry to publish packages to.
* xtask/publish: Don't release `xtask` subcrate
because it's not meant to be released at all.
* xtask/publish: Add status messages to publish
so we see what crate is currently being published, too.
* xtask/publish: Disable default features on `zellij`
because otherwise it tries to pick up the debug builds of the plugins,
which aren't part of released version of `zellij utils`.
* xtask/publish: Fix handling of custom registry
* docs: Add `RELEASE.md`
which explains how to simulate a zellij release.
* xtask: Apply rustfmt
* xtask: Remove `wasm-opt` from build steps
because recent versions cause havoc in the release process in GitHub
pipelines and it's primary goal is to only reduce binary size. Current
rust versions seem to produce very compact wasm binaries themselves,
though.
* .github: Don't install wasm-opt in workflows
