Bug fix for hover and navigation

[noklam]

Context

Currently the cursor is not parsing the correct word when hover over or select namespaced parameters/catalog. For example
params:a.b.c should be parsed as a to retrieve the top-level key.

A better approach of this is a back up search:

1. Find a.b.c
2. If not, find a instead

This is a bit tricky because how Kedro users use this inconsisently. For example, in pipeline.py it is always a one-line string:
params:a.b.c, namespace.dataset

In YAML, catalog are defined as oneline:

namespace.dataset:
  key: value

while in parameter file, it is defined as nested key:

top:
  med:
    key: value

So we need to handle this in a 2-steps process in general:

1. Determine if it's a parameters
2. Use the corresponding logic to parse out the "target" word