use new feature xmin/xmax of SummationByPartsOperators.jl

[ranocha]

I added (non-exported) interface functions xmin(D) and xmax(D) to SummationByPartsOperators.jl. This allows us to query the boundary of the domain specified when constructing the SBP operator. This allows us to unify the scaling code for general (periodic and non-periodic) SBP operators and should be used in #1014. The final goal should be to unify the interface there:

• It doesn't matter which domain you chose when constructing the SBP operator
• All SBP operators will be mapped to [-1, 1] internally
• The real domain is specified when constructing the mesh in Trixi.jl

[codecov]

Codecov Report

Merging #1015 (e906e84) into main (c90edae) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1015   +/-   ##
=======================================
  Coverage   94.06%   94.06%           
=======================================
  Files         291      291           
  Lines       22420    22421    +1     
=======================================
+ Hits        21088    21089    +1     
  Misses       1332     1332           

Flag	Coverage Δ
unittests	94.06% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/solvers/dgmulti/sbp.jl	95.81% <100.00%> (+0.03%)	⬆️

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[jlchan]

Looks good, thanks!