Fix removeColumn() throwing "Worksheet no longer exists" on a sheet with a table

[aswinkumar863]

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

Why is this change needed?

Fixes #5058.

Removing (or inserting) a column that moves the header row of a table throws Worksheet no longer exists.

When a header cell changes, Cell::setValueExplicit() calls updateIfCellIsTableHeader(), which updates the structured references in all formulas. It reads those cells with getCell(), and that detaches the cell we are setting. After that, setValueExplicit() calls $this->getWorksheet() and fails.

The fix keeps the cell collection in a variable and gets the cell again after the header update, so it is attached again before its worksheet and style are used.

Added ColumnInsertRemoveTest with 3 tests. The column A test fails without the fix. The full test suite passes.

This is a different problem from #5050 (that one is in the loop at the end of Worksheet::removeColumn()).

[dkulyk]

While testing this branch: after removeColumn() on a sheet with a table, a structured reference to a removed column is rewritten to the column that moves into its place, instead of becoming #REF!.

$sheet->fromArray([['Name', 'Qty', 'Price'], ['a', 1, 2], ['b', 3, 4]]);
$sheet->setCellValue('J1', '=COUNTA(Sales[Name])');
$sheet->setCellValue('J2', '=SUM(Sales[Qty])');
$sheet->setCellValue('J3', '=SUM(Sales[Price])');
$sheet->addTable(new Table('A1:C3', 'Sales'));
$sheet->removeColumn('B');

Column removed	Excel for Mac	This branch (56cec70)
A	=COUNTA(#REF!)	=COUNTA(Sales[Qty])
B	=SUM(#REF!)	=SUM(Sales[Price])
C	=SUM(#REF!), table A1:B3	=SUM(Sales[]), table stays A1:C3

ReferenceHelper::insertNewBefore() moves the cells with setValueExplicit(), and Cell::updateIfCellIsTableHeader() takes the header changing from Qty to Price for a rename and runs Table\Column::updateStructuredReferences().

Outside the scope of this PR; noting it here as it is the same code path.