The dump functionality works both for files and REPL.

With --dump-tokens or -t for short it dumps the token stream to stdout  and --dump-ast or -a for short to dump the ast to stdout.

The dumping of tokens and ast is mutually exclusive. and when dumping it wont run the code.

- Changed the --dump-tokens and --dump-ast to be an optional argument that optionally takes a value of format type ([--opt=[val]]).
- The default format for --dump-tokens and --dump-ast is Debug format which calls std::fmt::Debug.
- Added Json and JsonMinified format for both dumps,  use serde_json internally.
- It is easy to support other format types, such as Toml with toml-rs for example.

- Serde serialization and deserialization can be switched on by using the feature flag "serde-ast".

- Now Json  dumping format prints the data in minefied JSON form by default.
- Removed JsonMinified.
- Added JsonPretty as a way to dump the data in pretty printed JSON format.