scm: tree-search should highlight matched nodes

[vince-fugnitto]

Bug Description:

The tree-search for scm should properly highlight matched nodes like in other areas (ex: explorer).
At the moment, nodes are not highlighted which is both confusing and inconsistent with the rest of the framework.

Steps to Reproduce:

1. start the application, perform changes and open the scm view
2. type to start the tree-search
3. notice how no highlights are present

[colin-grant-work]

The problem here seems to be that TreeSearch relies on this to get the string to filter on:

(node: TreeNode) => this.labelProvider.getName(node);

But the SCM tree itself extracts the URI from a node before it asks the label provider for the name:

const name = this.labelProvider.getName(new URI(node.sourceUri));

I'll look into reconciling the behavior.