Misc: Remove isProp

[HoshinoTented]

This PR:

• Remove the uses of isProp in TermComparator

[codecov]

Codecov Report

Merging #1011 (40e1859) into main (8682036) will decrease coverage by 0.03%.
Report is 8 commits behind head on main.
The diff coverage is 85.71%.

@@             Coverage Diff              @@
##               main    #1011      +/-   ##
============================================
- Coverage     81.82%   81.79%   -0.03%     
+ Complexity     3500     3471      -29     
============================================
  Files           288      287       -1     
  Lines         10694    10640      -54     
  Branches       1296     1281      -15     
============================================
- Hits           8750     8703      -47     
+ Misses         1217     1216       -1     
+ Partials        727      721       -6     

Files	Coverage Δ
base/src/main/java/org/aya/concrete/Expr.java	85.38% <100.00%> (-0.26%)	⬇️
.../main/java/org/aya/concrete/desugar/Desugarer.java	78.46% <ø> (-0.33%)	⬇️
base/src/main/java/org/aya/core/def/CtorDef.java	60.00% <ø> (-6.67%)	⬇️
base/src/main/java/org/aya/core/term/SortTerm.java	80.00% <ø> (-8.89%)	⬇️
base/src/main/java/org/aya/generic/SortKind.java	100.00% <100.00%> (ø)
base/src/main/java/org/aya/tyck/ExprTycker.java	83.85% <100.00%> (-0.10%)	⬇️
base/src/main/java/org/aya/tyck/StmtTycker.java	90.59% <100.00%> (-1.00%)	⬇️
...e/src/main/java/org/aya/tyck/pat/ClauseTycker.java	95.71% <100.00%> (-0.12%)	⬇️
...src/main/java/org/aya/tyck/pat/PatternProblem.java	93.65% <ø> (-0.38%)	⬇️
.../src/main/java/org/aya/tyck/pat/PatternTycker.java	89.44% <100.00%> (+0.91%)	⬆️
... and 7 more

... and 2 files with indirect coverage changes

[ice1000]

Let me do more