Convert to v2, addon. Just wrap fetch.

[NullVoxPopuli]

This PR is (what I think is) the goal.
We can decide if we want to move towards this goal incrementally or deciding that this is what we want and skip all the in-between.

To move incrementally, we'd need to resolve the following PRs:

• [DO NOT MERGE] Fork of Pixelik's PR to fix tests and security issues #753
• update to v3.28 with ember-cli-update #743
• drop support for node < 16 #742
• breaking: drops Ember < 3.28, upgrades to Ember 4.12, supports Ember 5 #741
• Move to new ember-fetch import path #732

Which... we can do -- I'm not sure it's worth keeping CI green through all that though. ember-fetch is in a bit of disrepair.

Support:

• 3.28+ (easily), maybe 3.4+
• ember-auto-import @ v2+ or embroider
• @ember/test-waiters v3+
• any node (node doesn't matter anymore)
• continue the renamed-modules support (import from fetch)

I'm not sure what the fastboot support story would be, but Node natively has fetch, AbortController, etc.

Dropped Support:

• Configuration: PREFER_NATIVE, NATIVE_PROMISE
• jQuery AJAX
• You no longer import AbortController. AbortController exists on globalThis
• You no longer import Headers. Headers exists on globalThis
• You no longer import Response. Response exists on globalThis

Since ember-auto-import tests against 3.4.0, and ember-auto-import is the only real requirement for this change, there is no change in supported ember-source.

If anything, the constraining function is @ember/test-waiters

Changes:

• delete the old addon
• create new fetch export
• copy over old utils as separate exports
  • remove './types', because these exist all natively
  • remove './utils/determine-body-promise' because it used jQuery AJAX options
  • remove './utils/mung-fetch-options' because it used jQuery AJAX options
• no build -- folks can just point at git to test this
• separate test app
• yarn -> pnpm

After this PR:

• Add release plan
• remove release-it

[bertdeblock]

There's also https://github.com/knowledgecode/jquery-param, so wondering if we should still include this in ember-fetch?

[NullVoxPopuli]

Todo (RFC):

• remove ember-fetch from blueprints
• write docs for the guides on "centralized place to manage requests"

Todo (This PR):

• waitForPromise around the response.json() and response.body()
• get reviewed, merge