New functionality with tags picker via :ObsidianTags

[epwalsh]

#447 added some exciting new functionality to our picker integrations, and in particular for picking tags. Here is a demo where I'm using telescope as my picker. Note:

• Only a subset of this functionality is available with the alternative pickers (fzf-lua and mini.pick) due to their more limited Lua APIs.
• I'm using a which-key mapping here to call the :ObsidianTags command.
• Within the picker windows I use the default mappings of <TAB> to mark an entry for selection, <c-x> to add a tag to the current note, <c-l> to insert a tag at the cursor location, and <CR> to search for locations of the selected tags across my vault.