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.
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.
