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.
* Breaking Change to toFormattedString and 3 toArray Methods
DocBlock says `toFormattedString` returns string, but code can return int, float, bool, null, or RichText. I think the DocBlock is correct (function name clearly indicates "to string"), and the code needs to change to match it. This is not that big a deal on its own. However, some methods in `Worksheet` call this function by default - `rangeToArray`, `toArray`, and `namedRangeToArray`. All 3 can be called with a parameter so that they don't call `toFormattedString`, but, by default, they do call, and so are affected by this change. Some unit test results are changed as a result of this code change. In all those cases, an additional test is added which would match the previous result.
* Update Change Log
I often skip this till later, but, since it's a breaking change ...
* Scrutinizer, Plus Strange Cast to -0
Avoid Scrutinizer complaint by casting string to float, but ... Php decides resulted should sometimes be `-0`? That caused test failures. Very odd.
`Worksheet::getCell()` used to optionnaly return null if passed a
second argument. This second argument was removed entirely and the
method always returns a Cell (possibly creating it if needed).
This make the API more predictable and easier to do static analysis
with tools such as PHPStan.
If you relied on that second parameter, you should instead use the
`Worksheet::cellExists()` before calling `getCell()`.