Add a guide on "How do I become a Node.js committer". #26287

It wasn't perfect, but we used to do a better job of this.

A long time ago we used to say this in CONTRIBUTING.md:

The Node.js project has an open governance model and welcomes new contributors.
Individuals making significant and valuable contributions are made
Collaborators and given commit-access to the project. See the
GOVERNANCE.md document for more information about how this
works.

And GOVERNANCE.md used to say:

Individuals identified by the TSC as making significant and valuable
contributions across any Node.js repository may be made Collaborators and given
commit access to the project. Activities taken into consideration include (but
are not limited to) the quality of:

• code commits and pull requests
• documentation commits and pull requests
• comments on issues and pull requests
• contributions to the Node.js website
• assistance provided to end users and novice contributors
• participation in Working Groups
• other participation in the wider Node.js community

If individuals making valuable contributions do not believe they have been
considered for commit access, they may log an issue or contact a TSC member
directly.

I agree.

Just to follow up, the best we currently have is the Collaborator Nominations section of GOVERNANCE.md, although this is written more for the person making the nomination as opposed to the person who would like to become a collaborator.

I think we should restore some of the original text, somewhere.

I want to note that this is still an issue. As someone new to open-source and contributing, I think Node.js could do a lot better job welcoming new contributors. Reading the CONTRIBUTING.md just now, I wasn't sure if new contributors were even welcome, or how to get involved. This could be rewritten/restored to help new people feel more welcome.

Please review #38056.