List stored procedures and functions

[paultatulea]

Similar to table schema, list available stored procedures and functions. Allow user to create a new buffer with the stored procedure / function code.

[matteoquintiliani]

I started developing to add the feature to list procedures and functions.

I also added the basic helpers to get their respective definitions and sources.

At the moment I have only developed for PostgreSQL and MySQL. It is necessary to extend the development for other types of DBMS.

The 2 main commits are:

• https://github.com/matteoquintiliani/vim-dadbod/commit/1b673d827448789e8d418b1368bf713e0aca37ca
• https://github.com/matteoquintiliani/vim-dadbod-ui/commit/00c342e825762f9cb50aea9888ae5a8a550aa4ce

If you consider my approach to be valid, I am available to proceed with a PR on this official project.

[matteoquintiliani]

A screenshot