Use isValidIndex function internally in h3.c

[ritoban23]

Use isValidIndex function internally #1060

This PR addresses issue #1060 by replacing manual validation checks with the unified isValidIndex function in the CLI application.

Changes

• Updated 5 CLI subcommands to use H3_EXPORT(isValidIndex)(cell) instead of manual OR checks:
  • getResolution
  • getBaseCellNumber
  • getIndexDigit
  • isResClassIII
  • isPentagon

Testing

• ✅ Project compiles successfully
• ✅ All modified functions work with cells, directed edges, and vertices
• ✅ Invalid inputs are properly rejected
• ✅ 99% of existing tests pass (2 unrelated failures)

Files changed: src/apps/filters/h3.c

[CLAassistant]

All committers have signed the CLA.

[coveralls]

coverage: 98.936%. remained the same
when pulling d3c35b5 on ritoban23:use-isvalidindex-internally
into 1cbc65f on uber:master.

[ajfriend]

Thanks! LGTM