Remove setting to disable formatting

[alzimmermsft]

Removes the setting that disables code formatting as generated code should always be formatted. This is likely a hold over when code formatting was rapidly changing to prevent too much noise.

Additionally, there is a lot of cleanup of code patterns to reduce Pattern usage and String.format (when reasonable) to increase performance. And reduction of collecting streams to List when an Iterator is sufficient.

[weidongxu-microsoft]

This flag was mainly for skip formatting, when generated code cannot pass formatting (sometimes due to incorrect option, e.g. invalid namespace; sometimes due to bug in codegen).