Search through the tree's nodes

Add a search function to find loaded nodes matching the filter. The filter will support smart tokenization for camelCase, PascalCase, snake_case, for example:

- Let the identifiers "foo_baz", "FarBaz", "fireBaz"
- Search with `fbaz`
- Search should match 
  - <ins>**f**</ins>oo_<ins>**baz**</ins>
  - <ins>**F**</ins>ar<ins>**Baz**</ins>
  - <ins>**f**</ins>ire<ins>**Baz**</ins>