Expose both created `MeiliSearch` instance, and the used `meilisearch` package

[F. Levi]

Currently if one wishes to check, for example, the total number of documents on an index, they need to install the meilisearch package as well, and they cannot reuse the already created MeiliSearch instance that @meilisearch/instant-meilisearch creates. This introduces another potential problem, which is that the version which @meilisearch/instant-meilisearch uses and the one that is separately installed is mismatched, resulting in a larger bundle.
This can be avoided by exposing all of meilisearch package from @meilisearch/instant-meilisearch and also exposing the created instance, sort of like how #1258 will expose the search parameters.

[F. Levi]

I looked into this problem a bit, exposing the created MeiliSearch instance is very easy with #1258 being implemented, however exposing the used meilisearch package is at least a little questionable. I wanted to use the package.json exports field to achieve this, but that would've involved messing with bundling, and also it just flat out wouldn't have worked with UMD. Bummer.

I am considering exposing it in index.ts like so:

export * from './client'
export * from './types'
export * as meilisearch from 'meilisearch'

This shouldn't cause any issues, theoretically.