Audit handler clean-up and bug fixes

[david-russo]

• Prevented handler from crashing when file information lacks MIME type.
• Grouped and reported any files which lack MIME types in the MIME type summary.
• Replaced "not found" and "not processed" status values with "unknown" to align with other reports.
• Added in-report documentation for how to interpret the summary values.
• Corrected summary counts of well-formed files (they previously also included malformed files).
• Expanded summary values to include counts for "not well-formed" and "unknown" files.

NB: This pull request contains code reformatting, so see individual commits for clearer change sets.

[codecov]

Codecov Report

Merging #411 into integration will decrease coverage by 2.9%.
The diff coverage is 7.6%.

@@                Coverage Diff                @@
##             integration     #411      +/-   ##
=================================================
- Coverage          52.71%   49.81%   -2.91%     
+ Complexity          1119      976     -143     
=================================================
  Files                 55       55              
  Lines               9343     7633    -1710     
  Branches            2284     1377     -907     
=================================================
- Hits                4925     3802    -1123     
+ Misses              3890     3372     -518     
+ Partials             528      459      -69

Impacted Files	Coverage Δ	Complexity Δ
...arvard/hul/ois/jhove/handler/audit/AuditCount.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...arvard/hul/ois/jhove/handler/audit/AuditState.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...du/harvard/hul/ois/jhove/handler/AuditHandler.java	9.21% <9.79%> (ø)	2 <2> (ø)	⬇️
.../java/edu/harvard/hul/ois/jhove/ConfigHandler.java	59.66% <0%> (-9.57%)	27% <0%> (-23%)
.../edu/harvard/hul/ois/jhove/handler/XmlHandler.java	63.07% <0%> (-8.04%)	274% <0%> (-80%)
...c/main/java/edu/harvard/hul/ois/jhove/Message.java	80% <0%> (-8%)	10% <0%> (-2%)
...main/java/edu/harvard/hul/ois/jhove/JhoveBase.java	42.79% <0%> (-5.86%)	42% <0%> (-36%)
...edu/harvard/hul/ois/jhove/handler/TextHandler.java	0.54% <0%> (-0.1%)	2% <0%> (-2%)
...rvard/hul/ois/jhove/messages/JhoveMessageImpl.java	83.33% <0%> (+60.6%)	5% <0%> (ø)	⬇️

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