Support for previewing assessment items

Auditors: eater
cars no longer parkses
Merge pull request #45524 from Christi/plurals

cars no longer parkses
minor fix in response to #45496
Merge pull request #45537 from Christi/plurals2

minor fix in response to #45496

fix #45496; fix #45553
Change strange odd/even wording for exponents 1

Auditors: eater
Don't show 0-weight problem types in ex browser

Also change "0: horizontal" to "#1: horizontal" as well as changing "0: 0"
(with unnamed types) to simply "#1".

Auditors: eater
Revert linting changes.
Replace numeric degrees with symbolic label:

Due to rounding errors when converting to niceAngles,
the numeric value displayed can lead to invalid
triangles. i.e. an SSA triangle with side, side, angle
values that produces a triangle that does not exist.

This change is to just replace the numeric rounded value
displayed with a theta character to show that the angles
are equal and that the bisector theorem can be used.
Fix issue with congruent_triangles_2 not showing x

fix #45164; fix #45163; fix #45162; fix #45155; fix #45143; fix #45142;
fix #45141; fix #45140; fix #45134; fix #45125; fix #45105; fix #45101;
fix #45098; fix #45094; fix #45087; fix #45082; fix #45076; fix #45065;
fix #45057; fix #45044; fix #45034; fix #44966; fix #44928; fix #44817;
fix #36534; fix #32123

Test plan: http://localhost:8000/exercises/congruent_triangles_2.html?seed=62&problem=parr&debug note that "x" is shown.
Fix verb tense

Auditors: eater
Don't talk about the answer format in the question

Auditors: eater
Algebraic property wording tweaks

Auditors: eater
Resolve merge conflict.