Setup release-plan (using the generator) for the 2 packages that we need to have releasable in thsi repo that aren't ember-source

[NullVoxPopuli]

ember-source's release strategy is quite a bit simpler than release-plan (to me anyway -- perhaps because it's already set up, and I don't need to configure anything).

But, we need to release @glimmer/syntax -- it's coming up on a year of being unreleased 😬 and tooling consumers, such as prettier, ember-estree, ember-template-recast, etc all depend on that package.

Resolves:

• Get @glimmer/syntax publishable again and get some smoke tests going for prettier #21188 (comment)

Blocked on:

• Support filter.{only,exclude} release-plan/release-plan#247

Ref:

• Filterable packages beyond specifying private: true release-plan/release-plan#246

[github-actions]

📊 Size report

Tarball size — 1.2 MB → 1.2 MB

dist/dev   No changes

File	Before (Size / Brotli)	After (Size / Brotli)
./packages/shared-chunks/api-{hash}.js	10 kB / 2.1 kB	161%↑26.2 kB / 174%↑5.8 kB
Total (Includes all files)	2.1 MB / 498 kB	2.1 MB / 498 kB

---

dist/prod   No changes

File	Before (Size / Brotli)	After (Size / Brotli)
Total (Includes all files)	1.9 MB / 455.4 kB	1.9 MB / 455.4 kB

---

smoke-tests/v2-app-template/dist   No changes

File	Before (Size / Brotli)	After (Size / Brotli)
Total (Includes all files)	350.3 kB / 95.6 kB	350.3 kB / 95.6 kB

---

smoke-tests/v2-app-hello-world-template/dist   No changes

File	Before (Size / Brotli)	After (Size / Brotli)
Total (Includes all files)	132.6 kB / 37 kB	132.6 kB / 37 kB

_{🤖 This report was automatically generated by wyvox/pkg-size}