Agawrys/lightning css entries fix

[AGawrys]

↪️ Pull Request

This PR allows for bundles within the experimental bundler to have multiple entries, which fixes some test cases for the lightning-css branch

There's still a failing test from css-modules but it's not from this change, rather, its left over from the tests failing on the lightingcss branch

[parcel-benchmark]

Benchmark Results

Kitchen Sink ✅

Timings

Description	Time	Difference
Cold	2.00s	+108.00ms ⚠️
Cached	409.00ms	-33.00ms 🚀

Cold Bundles

Bundle	Size	Difference	Time	Difference
dist/legacy/parcel.7cdb0fad.webp	102.94kb	+0.00b	115.00ms	-227.00ms 🚀
dist/legacy/parcel.7cdb0fad.webp	102.94kb	+0.00b	117.00ms	-226.00ms 🚀
dist/modern/parcel.7cdb0fad.webp	102.94kb	+0.00b	117.00ms	-226.00ms 🚀

Cached Bundles

No bundle changes detected.

React HackerNews 🚨

Timings

Description	Time	Difference
Cold	FAILED	-0.00ms
Cached	FAILED	-0.00ms

Cold Bundles

No bundles found, this is probably a failed build...

Cached Bundles

No bundles found, this is probably a failed build...

AtlasKit Editor 🚨

Timings

Description	Time	Difference
Cold	FAILED	-0.00ms
Cached	FAILED	-0.00ms

Cold Bundles

No bundles found, this is probably a failed build...

Cached Bundles

No bundles found, this is probably a failed build...

Three.js ✅

Timings

Description	Time	Difference
Cold	7.36s	-346.00ms
Cached	347.00ms	-13.00ms

Cold Bundles

Bundle	Size	Difference	Time	Difference
dist/Three.js	580.02kb	+0.00b	5.00s	-435.00ms 🚀

Cached Bundles

No bundle changes detected.

Click here to view a detailed benchmark overview.

[devongovett]

Played around with this some more, and I think it's more complicated now (esp with manual shared bundles in the mix). It's not so easy to know which ones are "entries" or not. I implemented a different approach within the CSS packager in #8492 which traverses the bundle and collects any assets that are reachable from nowhere except the bundle root. That seems to work pretty well and solves the immediate issue. If we need support for multi-entry bundles for another purpose later we can revisit, but gonna close this one for now.