Improve publishing experience for JSS maintainers

[kof]

What want the release to do

• Manually set the version (or mb take it from changelog.md)
• Build with the new version, commit the size-snapshots with changes (or avoid them somehow), we use the verson in the JS build and this increases bundle sizes
• Update peer dependencies ([all] Fix peer deps #991)
• Make sure npm tag is set, e.g. an alpha release should not be published with dist tag "latest" otherwise all people get the update.
• Make it use the changelog.md and add its contents for the release to the release tag on github. This will send out an email to people who subscribed releases and they will get the changees.

[kof]

The way I just had to publish to workaround the problem with size-snapshot mismatch after version bump:

lerna version --no-commit-hooks --no-push 
yarn build 
yarn test
git commit -a --amend --no-edit
npx lerna publish 10.0.0-alpha.8 --dist-tag next --force-publish * --yes --amend --no-git-tag-version
git push 
git push --tags

[HenriBeck]

I think we can use the postversion npm hook for building, that hook should be run after bumping the version and before lerna commits the changes

[kof]

I think this is done now.