Fix prop types on file cluster (#207)

[stepan-anokhin]

Resolves #207 Resolves #391 Resolves #421

Other changes:

• Ensure /stats/extensions endpoint to return list of unique extensions in lower-case (complementary to #417)
• Prevent state updates on unmounted MatchGraph
• Prevent state updates on unmounted MetadataPane
• Fix invalid TaskProgress progress value.
• Migrate existing components to higher-level routing API.
• Migrate templates to generic query cache implementation.
• Migrate tasks to generic query cache implementation.
• Migrate objects to generic query cache implementation.
• Fix a couple of bugs in query cache (invalid entity upates, invalid total on entity insertion, invalid TTL in orphaned queries).