Fix dotplot rendering outside it's allowed bounds

[cmdcolin]

This is a quick fix for #1792

There was some indication in #1764

Instead of laboriously making everything worry about the defaults being geared for the LGV, I make it 0 and then lgv specific use cases can override

[codecov]

Codecov Report

Merging #1793 (3310bb9) into master (afdd9e4) will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1793      +/-   ##
==========================================
- Coverage   58.66%   58.61%   -0.05%     
==========================================
  Files         457      457              
  Lines       21193    21193              
  Branches     5016     5016              
==========================================
- Hits        12432    12423       -9     
- Misses       8451     8460       +9     
  Partials      310      310              

Impacted Files	Coverage Δ
packages/core/util/Base1DViewModel.ts	77.20% <ø> (ø)
...c/LinearGenomeView/components/OverviewScaleBar.tsx	91.89% <ø> (ø)
packages/core/util/blockTypes.ts	73.01% <0.00%> (-14.29%)	⬇️

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