More infotext standardization

[pappasam]

Standardize hover text and adjust signature accordingly

Hover text requires more information embedded inside of it than other
types of information text. Completion items have more structured
information than Hover text. For this reason, structured information is
provided directly in Hover text and omitted from the signature (which is
used everywhere).

Fixes #178

[pappasam]

@ericvw please test this out! If you think there are better ways to present this information across Hover, Completion, and Signature, I'm happy to consider any iterations in your PR as well

[ericvw]

@pappasam, thanks. I'll take a look and report back.

[ericvw]

Having jedi type: seems weird to me. I would call it type: because Jedi returns the canonical Python type names that type() would return.

The only other comment I have is the performance/slowness concerns I also raised in #179 (comment) when using get_type_hints(). It's not terrible in my testing, but it is definitely more noticeable compared to not using get_type_hints().

[pappasam]

Handled instead by #179 and cfd2e7a