chore(crypto-js): Add a release workflow for crypto-js

[Hywan]

This patch adds a new npm run publish script that:

1. Run npm run prepublish (which runs the build and test scripts),
2. Run wasm-pack publish.

Note 1: The prepublish script is using the $npm_execpath
environment variable instead of just “npm”, so that if someone is
using yarn or another JavaScript package manager, it should work
(not tested yet).

Note 2: wasm-pack publish is run without running wasm-pack login
before that. But we are updating the registry URL in the NPM
configuration file in the Github Action workflow, see below.

This patch then creates a new Github Action workflow that is triggered
when a new tag of the form matrix-sdk-crypto-js-v[0_9]+.* is
pushed. This workflow runs npm run publish basically, but before
that, it updates the NPM configuration file by setting a value for
//registry.npmjs.org/:_authToken. Thus, running wasm-pack login is
not necessary.

Supersedes and closes #900. Fixes #794.

Edit 🆕:

This patch updates the publish NPM script to explicitly run
wasm-pack pack to create the NPM package in the pkg/
directory. This patch also updates the Github Action workflow for the
matrix-sdk-crypto-js release, to create a new Github Release, with
the NPM package attached as an asset file.

[Hywan]

The differences with #900 are:

• wasm-pack is run from an NPM script, so the wasm-pack's version installed by NPM, i.e. that lands in bindings/matrix-sdk-crypto-js/node_modules/, along with wasm-opt etc. Everything is embedded.

• wasm-pack publish is used to publish the package on NPM, which runs npm publish behind the scene. We don't use any other Github Actions, like JS-DevTools/npm_publish which was used in Crypto-JS release infrastructure #900. Problem is: How to pass an auth token, because we don't want to run wasm-pack login, which runs npm login, which is an interactive command that reads the login and the password? We have a token! Well, my trick is to update the NPM configuration key //registry.npmjs.org/:_authToken to set our token as the key value here. That's what JS-DevTools/npm-publish is doing. Less code, less dependencies, less friction. I just hope it will work!

[gnunicorn]

but I have some questions...

[codecov]

Codecov Report

Merging #966 (331f8b3) into main (68107e6) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #966   +/-   ##
=======================================
  Coverage   80.35%   80.35%           
=======================================
  Files         110      110           
  Lines       15809    15809           
=======================================
  Hits        12704    12704           
  Misses       3105     3105           

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