WIP: Sc/p4est view

[SimonCan]

Structures that create a view on a p4est mesh, similar to the structured mesh views implemented earlier. This is intended to be used on coupled simulations, but can be used for un-coupled as well.

This is a 0th iteration and provides some basic framework for some of the more exciting features to come in the next PRs.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 96.73913% with 3 lines in your changes missing coverage. Please review.

Project coverage is 96.34%. Comparing base (480aea9) to head (820cf13).

Files with missing lines	Patch %	Lines
src/meshes/p4est_mesh_view.jl	95.95%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1761      +/-   ##
==========================================
- Coverage   96.34%   96.34%   -0.00%     
==========================================
  Files         470      471       +1     
  Lines       37497    37577      +80     
==========================================
+ Hits        36125    36201      +76     
- Misses       1372     1376       +4     

Flag	Coverage Δ
unittests	96.34% <96.74%> (-<0.01%)	⬇️

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[jmark]

LGTM!