Method for1d block fv

[MagalieHeinrich]

Added method for plotting via Plots.jl/Makie.jl for TreeMesh1D if the solver is BlockFV.
This is described in issue #30687 (Block finite volume methods).

I tested the methof with

trixi_include("../examples/tree_1d_blockfv/elixir_advection_basic.jl", n_nodes = 4, initial_refinement_level = 3); plot(sol)

which resulted in this graph

I also ran

trixi_include("../examples/tree_1d_dgsem/elixir_advection_finite_volume.jl", polydeg = 0, initial_refinement_level = 5); plot(sol)

which resulted in this graph

The idea behind comparing these is to verify the block finite volume method against the standard finite volume method at an identical global resolution.

Case DGSEM: An initial refinement level of 5 yields 2^5=32 cells.
Case BlockFV: The total resolution of a level 3 mesh (2^3=8 blocks) where each block is subdivided into 4 subcells is also 32 (8*4=32).

[github-actions]

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[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 96.86%. Comparing base (28bf3a9) to head (9957bc7).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/visualization/types.jl	97.14%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3095      +/-   ##
==========================================
- Coverage   96.88%   96.86%   -0.02%     
==========================================
  Files         647      647              
  Lines       50026    50068      +42     
==========================================
+ Hits        48466    48495      +29     
- Misses       1560     1573      +13     

Flag	Coverage Δ
unittests	96.86% <97.14%> (-0.02%)	⬇️

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[ranocha]

When you update the tests as discussed offline, can you please also add a test whethere the DGSEM with polydeg = 0 and the equivalent BlockFV discretizations result in (approximately) the same plot data?