While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
PR #3513, developed by @SaidkhojaIftikhor, has been stuck for some time awaiting tests. This is the second of three PRs to replace that one. This accomodates the use of slash as a delimiter in column names in Tables and Structured References. The source changes are very simple. Additional tests exercise all the source changes.
There is also a preg_quote call when a table is renamed. I have also changed it to accomodate slash, because it's the right thing to do. But ... I can't think how to test it. PhpSpreadsheet will not allow you to set a table name to a string containing a slash (a test is added to confirm), and, if I manually update the Xml in an Xlsx spreadsheet so that the name does contain a slash, Excel will, understandably, complain that the file is corrupt.