Exporter: Add match by the longest prefix

[alexott]

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Right now, exporter generates paths like this:

resource "databricks_notebook" "some_notebok" {
  source = "${path.module}/notebooks/dir1/dir2/notebook.py"
  path   = "${databricks_user.user.home}/dir1/dir2/notebook"
}

Even if we emit a dedicated object for the databricks_directory resource that matches the given directory. It could be solved by adding a new matching method to select a directory with the longest path to a given notebook.