Experiment for improved context control

[Pfeil]

Experimental, early WIP. This may contain breaking changes (we'll see) and then likely land in a v3.0.0, maybe.

Experiment to implement auto-control for the context without bringing it to invalid states.

Rough idea:

• Adding things to context is allowed (Explicitly? Implicitly?)
• Removing things is only possible under certain circumstances. One may ask for a cleanup of the context. There may exist cleanup requests for everything, or sub-elements like urls or key-value-pairs.
• Fixing typos or http->https replacements (inline value change) can be done by explicit methods to do so.
• All changes are only applied if validation after the change is successful (rollback otherwise). For example, values should be URIs/IRIs, and so on.
• Implicit cleanup could happen when exporting a crate.

Drawbacks:

• Likely will have performance impacts
• In the end, the implementation is likely breaking and requires deprecating methods in beforehand
• Editors that use ro-crate-java will also have less direct control over context (and need to adapt the pattern or we offer two implementations)