Implement hooks without using hooks

[developit]

This PR reimplements useSignal(), useComputed() and useEffect() without using preact/hooks. This should offer some performance advantages, because the three hooks we provide can all be implemented using the same very simple "indexed slot" mechanism, effectively an inline implementation of the useMemo hook.

There are some possible drawbacks here though: I don't know if this will mess up DevTools, and it's possible it would make Prefresh's job more difficult (though I also wonder if it gives Prefresh a useful way to differentiate between Signals and Hooks?).

[changeset-bot]

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Latest commit: 1207a26

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[github-actions]

Size Change: +106 B (0%)

Total Size: 67.2 kB

Filename	Size	Change
docs/dist/assets/index.********.js	835 B	-1 B (0%)
docs/dist/assets/signals.module.********.js	1.14 kB	-831 B (-42%)	🎉
docs/dist/assets/style.********.css	1.19 kB	-21 B (-2%)
docs/dist/basic-********.js	244 B	-2 B (-1%)
docs/dist/demos-********.js	4.22 kB	+868 B (+26%)	🚨
packages/preact/dist/signals.js	1.25 kB	+51 B (+4%)
packages/preact/dist/signals.mjs	1.19 kB	+42 B (+4%)

ℹ️ View Unchanged

Filename	Size
docs/dist/assets/client.********.js	45.7 kB
docs/dist/assets/jsxRuntime.module.********.js	282 B
docs/dist/assets/preact.module.********.js	4 kB
docs/dist/assets/signals-core.module.********.js	1.33 kB
docs/dist/assets/style.********.js	21 B
docs/dist/nesting-********.js	1.13 kB
docs/dist/react-********.js	239 B
packages/core/dist/signals-core.js	1.39 kB
packages/core/dist/signals-core.mjs	1.42 kB
packages/react/dist/signals.js	790 B
packages/react/dist/signals.mjs	764 B

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