Add option to color all the letters on all the reads to the pileup renderer

[cmdcolin]

Draw all bases in the pileup with a setting called "Per-base lettering" (alongside the "Per-base quality")

It is a nice sanity check for alignments viewing

[codecov]

Codecov Report

Merging #2847 (f13ee8f) into main (9dba0d9) will decrease coverage by 0.08%.
The diff coverage is 10.86%.

@@            Coverage Diff             @@
##             main    #2847      +/-   ##
==========================================
- Coverage   59.89%   59.80%   -0.09%     
==========================================
  Files         584      584              
  Lines       26528    26561      +33     
  Branches     6443     6446       +3     
==========================================
- Hits        15888    15884       -4     
- Misses      10326    10363      +37     
  Partials      314      314              

Impacted Files	Coverage Δ
...lugins/alignments/src/LinearPileupDisplay/model.ts	63.45% <0.00%> (-0.66%)	⬇️
...s/alignments/src/PileupRenderer/PileupRenderer.tsx	48.37% <4.87%> (-3.80%)	⬇️
.../src/LinearPileupDisplay/components/ColorByTag.tsx	100.00% <100.00%> (ø)
...iew/src/LinearGenomeView/components/CenterLine.tsx	91.66% <0.00%> (-8.34%)	⬇️
products/jbrowse-web/src/util.ts	27.27% <0.00%> (ø)

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