feat(morph_logger): basic implementation

[baransu]

Resolves: #25

Basic logger implementation based on https://github.com/expressjs/morgan. Not sure if we want this but seams pretty extensible accepting Custom(list(token)) format allowing us to add more tokens in the future.

I also created Headers.re file in morph moving all data structure related stuff and providing get_header function to easily get single header (used in logger to get request or response headers)

TODO:

• fix formatting - LSP is failing me :/
• add basic tests

[baransu]

Not sure why CI is failing 😞 https://github.com/reason-native-web/morph/runs/280516641#step:6:203