[refactor] Rename variables/files

[nam-hle]

• Rename variable/file names with trailing index, or containing span, maximum:
  • calculateCellWidthIndex.ts → calculateCellWidths.ts
  • calculateMaximumColumnWidthIndex.ts → calculateColumnWidths.ts
  • calculateRowHeightIndex.ts → calculateRowHeights.ts
• Rename index parameters (and index0, index1, ...) in forEach, map callbacks to be more meaningful one
• Rename variables name value to proper name

[coveralls]

Pull Request Test Coverage Report for Build 327

• 76 of 76 (100.0%) changed or added relevant lines in 13 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 325:	0.0%
Covered Lines:	342
Relevant Lines:	342

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💛 - Coveralls

[gajus]

:tada: This PR is included in version 6.6.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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