Support `@JsonFormat` for `String`, numbers, using String.format()

Seems like it would be nice to just support formats available via format Strings that `String.format()` uses.
Note that existing support for date/time values use different formatting; this should be fine, and if we want to for some reason support something from `java.text.Format` it should be possible to use heuristics to determine intended type of format. However that may not be necessary.

Initially we should just support simple types:
- `java.lang.String`
- `int`, `long`, `short`, `byte`, `float`, `double` and matching wrapper types
- `BigDecimal`, `BigInteger`