Register newly inserted import statement as a declaration in Babel scope

[andrewiggins]

When inserting a new import statement, we need to register it with Babel's scope tracking so future usages of the import are properly tracked to this declaration.

I've also removed CJS support currently since we don't have any tests for it and I'm uncertain if the maintenance burden if worth it. Open to suggestions.

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🦋 Changeset detected

Latest commit: 457fc4574acccdaba7f8feb9ff2bd61ab0f7a844

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-react-transform | Minor |

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Size Change: +1.59 kB (+2%)

Total Size: 79.6 kB

Filename	Size	Change
packages/react-transform/dist/signals-*********.js	3.51 kB	+720 B (+26%)	🚨
packages/react-transform/dist/signals-transform.mjs	2.82 kB	+160 B (+6%)	🔍
packages/react-transform/dist/signals-transform.umd.js	3.63 kB	+712 B (+24%)	🚨

ℹ️ View Unchanged

| Filename | Size | | :--- | :---: | | `docs/dist/assets/client.********.js` | 46.7 kB | | `docs/dist/assets/index.********.js` | 835 B | | `docs/dist/assets/jsxRuntime.module.********.js` | 281 B | | `docs/dist/assets/preact.module.********.js` | 4.02 kB | | `docs/dist/assets/signals-core.module.********.js` | 1.43 kB | | `docs/dist/assets/signals.module.********.js` | 2.02 kB | | `docs/dist/assets/style.********.js` | 21 B | | `docs/dist/assets/style.********.css` | 1.21 kB | | `docs/dist/basic-********.js` | 244 B | | `docs/dist/demos-********.js` | 3.35 kB | | `docs/dist/nesting-********.js` | 1.13 kB | | `docs/dist/react-********.js` | 238 B | | `packages/core/dist/signals-core.js` | 1.5 kB | | `packages/core/dist/signals-core.mjs` | 1.53 kB | | `packages/preact/dist/signals.js` | 1.27 kB | | `packages/preact/dist/signals.mjs` | 1.22 kB | | `packages/react/dist/signals.js` | 1.35 kB | | `packages/react/dist/signals.mjs` | 1.29 kB |

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