refactor(#1960): Refactor transformation rules, add schema restore

[dominikriemer]

Purpose

Refactor adapter schema transformation logic:

• Improve code structure
• Cleanup transformation logic
• Add capability to derive the original schema from transformation rules as a prerequisite for adapter modification (Better support modification of existing adapters #1960)
• Fix an issue that occurred when adding a new nested field in the schema editor (no runtime name assigned to added field)
• I also added a method getRulePriority to each transformation rule which determines the order of rule application, which was previously done implicitely.

Remarks

PR introduces (a) breaking change(s): no

PR introduces (a) deprecation(s): no

[bossenti]

Can we manage priorities somewhere centrally? E.g. via an enum?
With the current way it's hard to assess the individual priority value

[tenthe]

If this is not possible, I would suggest that we add a small explanation somewhere in the JavaDoc (e.g. at the interface) that briefly explains the concept of rulePriority.

[dominikriemer]

thanks, I modified the code to provide all priorities from an enum

[tenthe]

Is there a reason why all the visit methods are emtpy?

[dominikriemer]

I added a comment to the empty methods to clearly state that the operation is skipped for stateless rules

[tenthe]

Can we make the methods in this class none static? This is currently not critical, but if we change this, the clients that use the class should be easier to test. This comment also applies to the other Helper and Utils classes. We can also have a discussion about this.

[tenthe]

If this is not possible, I would suggest that we add a small explanation somewhere in the JavaDoc (e.g. at the interface) that briefly explains the concept of rulePriority.