Breaking Change to toFormattedString and 3 toArray Methods

[oleibman]

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.

This is:

- [x] 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
• Documentation is updated as necessary

Why this change is needed?

Provide an explanation of why this change is needed, with links to any Issues (if appropriate).
If this is a bugfix or a new feature, and there are no existing Issues, then please also create an issue that will make it easier to track progress with this PR.

[oleibman]

Not concerned with Scrutinizer "complexity" message.