Split tools, upgrade to Java 21

[ice1000]

As title, also write changelog

[codecov]

Codecov Report

Attention: 19 lines in your changes are missing coverage. Please review.

Comparison is base (9a364e9) 81.42% compared to head (1e74abb) 81.33%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
...c/main/java/org/aya/tyck/unify/TermComparator.java	0.00%	5 Missing ⚠️
...ain/java/org/aya/cli/literate/SyntaxHighlight.java	73.68%	1 Missing and 4 partials ⚠️
...main/java/org/aya/cli/library/LibraryCompiler.java	62.50%	3 Missing ⚠️
...e/src/main/java/org/aya/core/term/FormulaTerm.java	0.00%	2 Missing ⚠️
...c/main/java/org/aya/prettier/ConcretePrettier.java	50.00%	2 Missing ⚠️
...java/org/aya/pretty/backend/html/Html5Stylist.java	50.00%	1 Missing ⚠️
.../java/org/aya/pretty/backend/latex/TeXStylist.java	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1022      +/-   ##
============================================
- Coverage     81.42%   81.33%   -0.10%     
- Complexity     3462     3526      +64     
============================================
  Files           291      291              
  Lines         10789    10761      -28     
  Branches       1325     1307      -18     
============================================
- Hits           8785     8752      -33     
+ Misses         1271     1264       -7     
- Partials        733      745      +12     

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