ICU-23450 Fix undefined shift and buffer overflow in ubidi_writeReordered

[FrankYFTang]

In ubidi_writeReordered, if mirroring was enabled and a character
expanded during mirroring (e.g. U+221D mirrors to U+1DB10, expanding
from 1 to 2 UTF-16 code units), doWriteForward returned the expanded
length. ubidi_writeReordered then used this expanded length to index
dirProps at line 651, leading to out-of-bounds read and undefined shift.

This CL fixes this by:

1. Using the original run length to index dirProps in ubidi_writeReordered.
2. Fixing doWriteForward (mirroring and default cases) and doWriteReverse
   (default case) to correctly check destination buffer capacity during
   write, accounting for mirroring expansion, and perform correct preflighting.
3. Fixing a logical bug in doWriteReverse where copying of combining
   characters was using incorrect index due to assuming mirrored character
   has same length as original.

Adds unit tests to cintltst verifying the fixes.
Also add Java unit test and fix the java.

Checklist

• Required: Issue filed: ICU-23450
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-NNNNN Fix xyz"
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-NNNNN Fix xyz"
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable
• Approver: Feel free to merge on my behalf

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