Edoc diagnostics

[robertoaloi]

Description

This PR introduce support for edoc diagnostics.

There are a couple of limitations in the current edoc API:

• The list of errors and warnings is simply printed out using the stdio and not returned to the caller
• The process exits at the first error occurrence

An issue has been created for the OTP team to address these.
The current solution (ab)uses the process dictionary, a fork of the edoc_report module and a try/catch to temporarily circumvent these limitations.

This diagnostics backend is disabled by default. To enable it, add the following to your erlang_ls.config:

diagnostics:
  enabled:
    - edoc

Fixes #384.

[robertoaloi]

@garazdawi Do you know if it's a known fact that in OTP 24+ edoc does not generate documentation for files contained in a project priv directory?

[garazdawi]

Do you know if it's a known fact that in OTP 24+ edoc does not generate documentation for files contained in a project priv directory?

No, I don't know.