Update Chemistry MatchType priorities according to new feedback

[sjd210]

Similarly to other symbolic questions, in Chemistry we use a MatchType enum to keep track of the best match among a set of choices for a given question.

This enum should be set such that choices with less serious feedback (such as incorrect bracket-type) are seen as a closer match to the received answer than choices with more serious feedback (such as incorrect elements).

I hadn't touched these at all previously, so they've now been updated and extended to the range of feedback we can give

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I've also updated the type mismatch feedback so it specifically identifies which type has been input, and so it includes the Term type which thus far had been missing that chance for feedback.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 32 lines in your changes missing coverage. Please review.

Project coverage is 34.40%. Comparing base (d772ec7) to head (d1b4a9c).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...tg/isaac/quiz/IsaacSymbolicChemistryValidator.java	0.00%	32 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #660      +/-   ##
==========================================
- Coverage   34.42%   34.40%   -0.02%     
==========================================
  Files         521      521              
  Lines       23434    23444      +10     
  Branches     2873     2874       +1     
==========================================
  Hits         8066     8066              
- Misses      14556    14566      +10     
  Partials      812      812              

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