LSP: Inlay Hint support

WIP

TODO:

• config option
• test and fix issues with inlay hint update on text change
• reload hints on doc reload
• maybe don't fetch full doc inlayHint and only for the visible range and merge with existing inlayHints => opted for full doc because with "visible range", the text jumps too much and it looks very low quality. I can remove the delay and on fast computers it will be almost instant but you never know and some slow server will come around and trash your logic
• test inlay hint performance