Display impls use token formatting

[tiffany352]

Deduplicates a bunch of code by having Display impls use the TokenFmt implementations. There were some bugs with the TokenFmt formatting that I had to fix, and some slight differences in their output that required adjusting tests. This also fixes a longstanding bug where there were 2 spaces in the output, like 42 (dimensionless).

I also got rid of that two-step pattern parsing stuff, it's simpler to iterate the chars of the pattern string instead.

[codecov]

Codecov Report

Attention: Patch coverage is 69.35484% with 19 lines in your changes are missing coverage. Please review.

Project coverage is 81.97%. Comparing base (09c5163) to head (c90650a).

Files	Patch %	Lines
core/src/output/reply.rs	15.38%	11 Missing ⚠️
core/src/output/fmt.rs	69.56%	7 Missing ⚠️
core/src/output/number_parts.rs	96.15%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #183      +/-   ##
==========================================
+ Coverage   81.83%   81.97%   +0.13%     
==========================================
  Files          42       42              
  Lines        7885     7632     -253     
==========================================
- Hits         6453     6256     -197     
+ Misses       1432     1376      -56     

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