Switch to th_lira.plf (#3741)

Switch to th_lira.plf (#3741)

Switches arith_proof.cpp from th_lra to th_lira.

Changes:

Eliminate the d_realMode hack.
instead: modify printOwnedTermAsType prints as integers OR
reals, depending on expectedType.
simultaneously: write printOwnedTermAsType more concisely
also: reimplement printOwnedSort.
Change to the LIRA axioms:
Because they reason about bound types using side conditions, we
no longer need to worry about choosing the correct strictness for
our axiom.
This allows us to cut out a lot of code, rewriting & shrinking
printTheoryLemmaProof.
They also have different names.
This requires us to change a lot of string literals
enable proof-checking for many tests.