Integrate with changesets tool

[carterworks]

Warning

This PR is based off of #1412 and should be merged after it

Description

"Changesets" is "A tool to manage versioning and changelogs
with a focus on multi-package repositories".

The idea is that, when you are making changes to the repo that are public-facing, you will

• Run pnpm changeset
• Pick which packages facing
• Commit the generated markdown file.

The markdown file looks like this:

---
"@adobe/alloy": patch
---

Migrate the release process to use the changesets tool.

with this information, the ChangeSets tool will automate moving the version number. It can also handle alpha and beta releases by the pre-release mode.

Together with this change is a new release automation process. So this PR will set us into beta mode. And then there is a GitHub workflow that will, when there are changes that are public-facing and main is merged, it will automatically bump the version number and then release to NPM. When it is time to release the stable version, we will manually disable the pre‑release mode and then commit that to main where the change set tool and the new automation will automatically release that new stable version and then put us back into alpha pre‑release mode.

This replaces a lot of the custom scripts that we had. The bulk of the work went into the release. Focus/start your review efforts there.

Related Issue

Motivation and Context

Screenshots (if appropriate):

Checklist:

• I have signed the Adobe Open Source CLA or I'm an Adobe employee.
• I have made any necessary test changes and all tests pass.
• I have run the Sandbox successfully.