Experiment with different source/observer tracking mechanism

[milomg]

Summary

Use fused linked lists to make v1 signals faster.

Before:

createDataSignals: 4
createComputations0to1: 4
createComputations1to1: 8
createComputations2to1: 6
createComputations4to1: 5
createComputations1000to1: 4
createComputations1to2: 7
createComputations1to4: 6
createComputations1to8: 6
createComputations1to1000: 6
create total: 56
---
updateComputations1to1: 32
updateComputations2to1: 19
updateComputations4to1: 13
updateComputations1000to1: 23
updateComputations1to2: 27
updateComputations1to4: 26
updateComputations1to1000: 21
update total: 161
total: 217

After

createDataSignals: 2
createComputations0to1: 4
createComputations1to1: 6
createComputations2to1: 5
createComputations4to1: 4
createComputations1000to1: 4
createComputations1to2: 6
createComputations1to4: 6
createComputations1to8: 5
createComputations1to1000: 5
create total: 48
---
updateComputations1to1: 26
updateComputations2to1: 14
updateComputations4to1: 9
updateComputations1000to1: 11
updateComputations1to2: 20
updateComputations1to4: 18
updateComputations1to1000: 16
update total: 115
total: 163

How did you test this change?

pnpm run test (I'm not sure if our test coverage of Suspense will catch everything here though)

[changeset-bot]

🦋 Changeset detected

Latest commit: a49638c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
solid-js	Major
babel-preset-solid	Major
solid-element	Major
test-integration	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[coveralls]

Pull Request Test Coverage Report for Build 21104319443

Details

• 108 of 111 (97.3%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.0%) to 86.228%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/solid/src/reactive/signal.ts	108	111	97.3%

Totals
Change from base Build 18890830103:	1.0%
Covered Lines:	2415
Relevant Lines:	2729

---

💛 - Coveralls

[teleskop150750]

if (node.observers && node.observers) {