Implement support for sequences of compound types

[mattjala]

Variable-length sequences of compound datatypes could not be read or dispalyed due to being unsupported in compoundTypeIO(). This manifested as displaying ERROR instead of real data, without providing any clear output to the user about the root cause.

This PR implements a read path for the VLEN branch in compoundTypeIO, following the same pattern as for an array of compounds. In order to be able to display in a typical fixed-size table format, each cell displays all entries of a certain member in the vlen sequence as a string. e.g. If the datatype is a sequence of a cmpd type "coord" with fields 'lat' and 'long', there will be two distinct columns 'lat' and 'long'. Each row 'lat' column will contain all the 'lat' values for the sequence in that row, and the same is true for the 'long' cell in each row.

[github-actions]

🔍 Quality Analysis Report

Metric	Status	Value
Code Coverage	❌	Unknown
Quality Gate	✅ Passed	0 issues

Details

• Coverage Threshold: 60% minimum (non-blocking - JaCoCo integration issue)
• PMD Violations: Maximum 4000 allowed (progressive reduction target)
• Checkstyle: No errors allowed