If no thumbnail of the requested type exists, return a 404 instead
of erroring. This doesn't quite match the spec (which does not define
what happens if no thumbnail can be found), but is consistent with
what Synapse already does.

This was never used, so let's get rid of it.

Fixes / related to: https://github.com/matrix-org/synapse/issues/6533

This should do essentially the same thing as a robots.txt file telling robots to not index the media repo. https://developers.google.com/search/reference/robots_meta_tag



Signed-off-by: Aaron Raimist <aaron@raim.ist>

Replaces the `federation_ip_range_blacklist` configuration setting with an
`ip_range_blacklist` setting with wider scope. It now applies to:

* Federation
* Identity servers
* Push notifications
* Checking key validitity for third-party invite events

The old `federation_ip_range_blacklist` setting is still honored if present, but
with reduced scope (it only applies to federation and identity servers).

remove the stubbing out of `request.process`, so that `requestReceived` also renders the request via the appropriate resource.

Replace render() with a stub for now.

Where we want to render a request against a specific Resource, call the global
make_request() function rather than the one in HomeserverTestCase, allowing us
to pass in an appropriate `Site`.

If a file cannot be thumbnailed for some reason (e.g. the file is empty), then
catch the exception and convert it to a reasonable error message for the client.

The CI appears to use the latest version of isort, which is a problem when isort gets a major version bump. Rather than try to pin the version, I've done the necessary to make isort5 happy with synapse.

Closes #4382

Signed-off-by: Maxim Plotnikov <wgh@torlan.ru>

Migrate all tests to use the dict-based config format instead of hanging items off HomeserverConfig (#5171)