Replace instance variations of homeserver with correct case/spacing

synapse/__init__.py

synapse/_scripts/register_new_matrix_user.py

synapse/api/errors.py

synapse/config/captcha.py

synapse/config/emailconfig.py

synapse/config/server.py

synapse/federation/federation_client.py

synapse/federation/transport/__init__.py

synapse/federation/transport/client.py

synapse/federation/transport/server.py

synapse/handlers/auth.py

synapse/handlers/directory.py

synapse/handlers/federation.py

synapse/handlers/profile.py

synapse/handlers/register.py

synapse/handlers/typing.py

synapse/http/matrixfederationclient.py

synapse/util/httpresourcetree.py