Remove postinstall script

[elle-j]

What, How & Why?

Our bindgen:generate:typescript and bindgen:generate:wrappers scripts rely on the realm-bindgen command. For Bindgen's node dependencies in Core to be installed correctly and allow for the realm-bindgen command to be run, npm install needs to be run after git submodule update --init --recursive (which was previously in our postinstall script).

Replacing the postinstall with a preinstall does not fix this issue.

This PR removes the postinstall script all together, moving the responsibility of fetching the submodule to the developer:

git submodule update --init --recursive
npm install

# Now you can e.g. run tests (which will build etc. automatically).
npm run test --workspace realm # Unit tests

☑️ ToDos

--

[coveralls-official]

coverage: 85.397%. remained the same when pulling 021bfe9 on lj/bindgen-postinstall into eca95b6 on main.

[kraenhansen]

Any docs we need to update in https://github.com/realm/realm-js/tree/main/contrib as a part of this?

[elle-j]

@kraenhansen, regarding your comment if any of our contrib files also needs updating. In general I think we need to take a look at updating a lot of information when it comes to building and contributing (after bindgen was merged into main).

So unsure if any single update to those files with regard to this PR would be helpful, perhaps adding an npm install after this line.