Add option to use omnisearch rather than default Obsidian search on node click

[nickynicolson]

Clicking on a node in the rendered tree executes a search for the node label(s) in the vault, using the built in Obsidian search function.
A third party plugin omnisearch is available which indexes content from PDFs (e.g. the full text documents attached to literature references). It could be a useful enhancement to allow the user to specify that this should be used rather than the default search.
Would require a settings pane.