feat: introduce extended integration tests

- test both FLOSS and non-floss builds
- test on Synapse, Dendrite and Conduit
- remove Synapse-specific test
- add static Release mode app launch test

Signed-off-by: TheOneWithTheBraid <the-one@with-the-braid.cf>

scripts/integration-server-dendrite.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+chown -R 991:991 integration_test/dendrite
+
+# creating integration test SSL certificates
+docker run --rm --entrypoint="" \
+  --volume="$(pwd)/integration_test/dendrite/data":/mnt:rw \
+  matrixdotorg/dendrite-monolith:latest \
+  /usr/bin/generate-keys \
+  -private-key /mnt/matrix_key.pem \
+  -tls-cert /mnt/server.crt \
+  -tls-key /mnt/server.key
+
+ docker run -d --volume="$(pwd)/integration_test/dendrite/data":/etc/dendrite:rw \
+  --name dendrite -p 8008:8008 matrixdotorg/dendrite-monolith:latest -really-enable-open-registration
+
+sleep 20