Reconsider fast_diff_match_path license violation workaround

[LeonarddeR]

Is your feature request related to a problem? Please describe.

I have found some oddities in UnicodeNormalizationOffsetConverter that are related to difflib doing very odd things on the character level. I haven't been able to reproduce this with non-private content, though. Ideally I'd move to fast_diff_match_patch, but I don't want to change nvda_DMP just for this. This made me question the decision to create NVDA_DMP in the first place. Has this been discussed extensively in the past and if so, where?

Also note that from a python console, it is still possible to import fast_diff_match_patch. I wonder if this is actually allowed within the licensing provisions. There is some inconsistency here.

Describe the solution you'd like

I know about license compatibilities, but I'm also reading from Apache:

Despite our best efforts, the FSF has never considered the Apache License to be compatible with GPL version 2, citing the patent termination and indemnification provisions as restrictions not present in the older GPL license. The Apache Software Foundation believes that you should always try to obey the constraints expressed by the copyright holder when redistributing their work.

Long story short:

1. The incompatibility problem is not Apache's fault
2. The exceptions stated by the NVDA license should allow us to use FDMP from NVDA core directly when added as a GlobalPlugin bundled with core, because:
   • It does not prevent such a plugin from being licensed under the terms of the GPL v2
   • The component (i.e. FDMP) doesn't use NVDA internals itself)
   • If FDMP is only used by the plugin, the plugin can operate as a bridge between FDMP and NVDA

By the way, the license actually allows us to stretch the term plugin in the developer guide to such an extent that we can also classify parts of the core that stand alone but are not necessarily globalPlugins as plugins, making them subject to this license provision.

Describe alternatives you've considered

Refactor nvda_dmp in such a way that it returns the full diff, rather than only insertions.

Any thoughts @codeofdusk, @Danstiv

Originally posted by @LeonarddeR in https://github.com/nvaccess/nvda/issues/11548#issuecomment-2139287528