Librification

[V0ldek]

Is your feature request related to a problem? Please describe.
Before adding more features we should commit to librification of rsonpath.

Describe the solution you'd like
We need a clear separation between the binary CLI tool and the underlying library. To complete that, we need to:

• separate out a library crate, clean the dependencies of the library (Remove eyre as a library dependency and replace with thiserror #13, Remove the len_trait dependency #37);
• fix error handling (Make query parsing and compiling panic-free #38, Make query execution panic-free #39);
• and improve documentation (Add error and panic documentation #40)