Support a way to uppercase already written SQL

[jsborjesson]

Perhaps with a motion. This would probably also be a good opportunity to refactor the big list of keywords into a loop so it can be used for this too.

[qadzek]

Some options to accomplish this:

• An old plugin: https://github.com/vim-scripts/changesqlcase.vim
• Use SQLFluff and run something like :!sqlfluff format --dialect sqlite.
• A new plugin: https://github.com/michhernand/simple-sqlfluff.nvim