Build and/or document a way to manually provide documentation for a package

### Description

When processing a package fails (i.e. during transliteration), the respective per-language documentation will be missing for the end-user. However in certain situations it might still be easily possible to generate this documentation on a local machine (e.g. using a different bug-free version of jsii-docgen/jsii-rosetta, making a minor local change to the package in question etc).

In this situation it might be preferable to have a way to provide the documentation for a package out-of-band, while the issue is fixed properly.

### Use Case

We recently had an issue where language docs of aws-cdk-lib did not build due to an underlying issue. However locally generating the docs was still possible. If we had this feature, we could have mitigated the impact sooner.

If a high-impact package had an error that prevented processing for a good reason, but would be easy to fix in a local build we could use this mechanism to provide docs any way. Otherwise the package would have to release a new version but the affected version would never be able to receive a fix.

### Other information

This might already be possible with respective bucket access. We might just need to provide documentation and a script.