Add types to FileUpdaters::Base

[JamieMagee]

A couple of notable things I'd like to highlight about this PR:

• Reordered the parameters of initialize to fix Sorbet/KeywordArgumentOrdering: Optional keyword arguments must be at the end of the parameter list
• It's a little unclear what the types of credentials and options should be
  • I was more confident in credentials being T::Hash[String, String]
  • I was less confident in options so it's T::Hash[String, T.untyped]
• Methods marked with overridable should likely be marked as abstract, but abstract methods are required to have no body, and I am not sure if anything is depending on them raising a NotImplementedError
• Changes to other files are type system 'escape hatches' as they haven't been properly typed yet and I wanted to keep this PR small

Part of #7782

[jakecoffman]

Since it's a fundamental class I'll deploy it to see if there's any runtime errors before merging.