Add auto completion to the codeblock

[sytone]

There is an example implementation here: https://github.com/ytliu74/obsidian-pseudocode/blob/master/src/auto_complete.ts

It should be able to auto complete based on the yaml section it is in. So if in query then all the sql commands, known tables and functions.

For template all the known handlebars helpers.

It should know the render engine and query engine and switch the keywords off that if set.

For other settings it should be able to suggest the vaild options to help guide the users.