[Admin] Updates for the new ARC process.

[d0cd]

This PR contains updates for the new ARC process. This includes:

• clarified rules on how to propose and ARC and how it progresses.
• migration of ARCs from vote.aleo.org.
• updates to existing ARCs.
• PR templates.

New ARCs

The following ARCs have been retroactively added:

• ARC-0021 | @evanmarshall
• ARC-0030 | @evanmarshall, @fulltimemike (Note that this marked Deprecated in favor of self.signer)
• ARC-0042 | @HarukaMa
• ARC-0100 | @apruden2008
• ARC-0101 | @zkxuerb
• ARC-0721 | @pa-long

Thank you all for your contributions!
I took a first stab at importing your ARCs, however I wanted to reach out and confirm that it accurately reflected your proposals.
Feel free to reach out with any changes that you'd like incorporated!
We aim to merge this PR on 2024-01-27, please try to get your changes in by then.

Updates to existing ARCs

The following merged ARCs have been updated:

• ARC-0002 | Updated status to Living.
• ARC-0004 | @acoglio, @bendyarm. This ARC had to be removed as it has not been voted on. Based on the new rules (included in this PR), I recommend opening up a discussion thread (if necessary) and filing a new PR.

[zklim]

Lgtm! Should we sync the naming of tabs on https://vote.aleo.org/ to Accepted and Final / Living too?

[zklim]

This is for another time but is it better if Deprecated are grouped together in another directory for easier navigation on only Final / Living ARCs?

[d0cd]

I see the vision. As a counterpoint, it makes it slightly harder to check which ARCs have been taken.