Explorable Dependency Versioning

[salmenf]

• On saving an explorable:

1. Write an importmap with the versions of all widgets used in the explorable (based on installed).
2. Create bundle based on importmap.

• On loading an explorable:

1. Load importmap of explorable if available.
2. For each import:
3. If versions match, pass.
4. If explorable < installed on a minor or patch version, silently upgrade explorable.
5. If versions don't match: Let user choose between keeping both, aligning installed, or aligning explorable. Warn if aligning a major version mismatch.

• Also add a form in the metadata editor to change versions.