feat(core): add unique identifier for signals

[JoviDeCroock]

fixes #402

This allows for multiple versions of signals to be in a bundle and still be properly identified as signals.

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🦋 Changeset detected

Latest commit: 87b589bba898bd8e0683b99299ec963c6426c7d1

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

This PR includes changesets to release 1 package

| Name | Type | | -------------------- | ----- | | @preact/signals-core | Minor |

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Size Change: +91 B (0%)

Total Size: 78.1 kB

Filename	Size	Change
docs/dist/assets/client.********.js	46.7 kB	-5 B (0%)
docs/dist/assets/index.********.js	833 B	-2 B (0%)
docs/dist/assets/signals-core.module.********.js	1.46 kB	+31 B (+2%)
docs/dist/assets/signals.module.********.js	2.02 kB	+1 B (0%)
docs/dist/demos-********.js	3.35 kB	+1 B (0%)
packages/core/dist/signals-core.js	1.54 kB	+35 B (+2%)
packages/core/dist/signals-core.mjs	1.56 kB	+30 B (+2%)

ℹ️ View Unchanged

| Filename | Size | | :--- | :---: | | `docs/dist/assets/jsxRuntime.module.********.js` | 281 B | | `docs/dist/assets/preact.module.********.js` | 4.02 kB | | `docs/dist/assets/style.********.js` | 21 B | | `docs/dist/assets/style.********.css` | 1.21 kB | | `docs/dist/basic-********.js` | 244 B | | `docs/dist/nesting-********.js` | 1.13 kB | | `docs/dist/react-********.js` | 238 B | | `packages/preact/dist/signals.js` | 1.27 kB | | `packages/preact/dist/signals.mjs` | 1.22 kB | | `packages/react-transform/dist/signals-*********.js` | 2.79 kB | | `packages/react-transform/dist/signals-transform.mjs` | 2.66 kB | | `packages/react-transform/dist/signals-transform.umd.js` | 2.91 kB | | `packages/react/dist/signals.js` | 1.35 kB | | `packages/react/dist/signals.mjs` | 1.29 kB |

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[JoviDeCroock]

@marvinhagemeister do you agree with brand as the property name, had to change it due to type conflicting with ReactElement

[marvinhagemeister]

@JoviDeCroock brand is fine. Fits in line with the whole "branded types" idea