ci: release and publishing automation

[smallstepman]

Description

This PR:

• Reimplements the release and publishing process as described in the updated CONTRIBUTING.md file
• Overhaul the docs cause a lot of the information was outdated. Moves info from README.md and docs/npm-publish.md and consolidates it in CONTRIBUTING.md.

Implements https://dfinity.atlassian.net/browse/SDK-1188

How Has This Been Tested?

Manually, on fork: https://github.com/smallstepman/agent-js

Checklist:

• My changes follow the guidelines in CONTRIBUTING.md.
• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.

[github-actions]

size-limit report 📦

Path	Size
@dfinity/agent	88.39 KB (0%)
@dfinity/candid	13.58 KB (0%)
@dfinity/principal	5.2 KB (0%)
@dfinity/auth-client	92.68 KB (0%)
@dfinity/assets	90.81 KB (0%)
@dfinity/identity	89.96 KB (0%)
@dfinity/identity-secp256k1	233.63 KB (0%)