Create batch changes flow breaks when query contains unescaped characters

Created by: malomarrec

Current state

Creating a batch change from this doesn't "just work": https://demo.sourcegraph.com/search?q=context:global+fork:yes+repo:%5Egithub%5C.com/yowayb/uBlock%24+file:package.json+%22scaling-palm-tree%22:+%22...%22&patternType=structural

Error: Failed to normalize JSON: yaml: line 6: mapping values are not allowed in this context

Impact

https://sourcegraph.slack.com/archives/CMMTWQQ49/p1657717252405149

Desired state

Quote the search string to avoid this