Replace ArrayList in InputProcessorProfiles with fixed-size array, reduce allocations

[h3xds1nz]

Description

Loosely follows #9221, replacing the other part of the InputLanguageSource.InputLanguageList with more modern code.

• Instead of marshalling the array members, we just wrap the array in a ReadOnlySpan<short>.
• Instead of using ArrayList, we preallocate the array as we know the final count.
• The class can be sealed, no reason not to as it has no children.
• I've formatted the file and cleared unused usings for clarity.

Single invocation of the property (without _ipp init); 5 profiles

Method	Mean [ns]	Error [ns]	StdDev [ns]	Gen0	Code Size [B]	Allocated [B]
Original	556.4 ns	5.70 ns	5.33 ns	0.0696	1,245 B	1176 B
PR_EDIT	443.8 ns	4.42 ns	3.69 ns	0.0563	394 B	944 B

Customer Impact

Improved performance, decreased allocations.

Regression

No.

Testing

Local build, testing new output matches the old one.

Risk

Low.

Microsoft Reviewers: Open in CodeFlow

[dipeshmsft]

LGTM, @h3xds1nz can you please resolve the merge conflict here as well.

[h3xds1nz]

@dipeshmsft Done :)

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Project coverage is 13.58849%. Comparing base (c572f8e) to head (68366c2).
Report is 9 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main       #9946         +/-   ##
===================================================
- Coverage   13.62756%   13.58849%   -0.03908%     
===================================================
  Files           3316        3317          +1     
  Lines         664822      664754         -68     
  Branches       74651       74642          -9     
===================================================
- Hits           90599       90330        -269     
- Misses        571523      571829        +306     
+ Partials        2700        2595        -105     

Flag	Coverage Δ
Debug	13.58849% <0.00000%> (-0.03908%)	⬇️

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