ENH: nested grid with optional upscaling mappings

[lahus-0]

Add optional input of upscaling mappings from a geogrid to the input grid. These are then updated to map to the resulting nested hybrid grid. For situations where the geogrid and input grid are not perfectly aligned in structure due to the differences in resolution. This ensures that a proper mapping between cells in geogrid to nested hybrid grid can be maintain when both are originally sourced from same grid.

Main documentation will likely include the addition of an example workflow in drogon after this is all finalised.

Checklist

• Tests added (if not, comment why)
• Test coverage equal or up from main (run pytest with --cov=src/ --cov-report term-missing)
• If not squash merging, every commit passes tests
• Appropriate commit prefix and precise commit message used
• All debug prints and unnecessary comments removed
• Docstrings are correct and updated
• Documentation is updated, if necessary
• Latest main rebased/merged into branch
• Added comments on this PR where appropriate to help reviewers
• [?] Moved issue status on project board
• Checked the boxes in this checklist ✅

[lahus-0]

I'll merge all the other recent changes on nested hybrid grid setups with this and update next week to resolve the conflicts.

[lahus-0]

merged with all the other changes to nested hybrid grid setup.

[lahus-0]

adapted to fit with change of NestedHybridGrid into a class