refactor: improve redis client and publisher

- Refactor the redis client to use a mutex for thread safety.
- Improve error handling in context and playbook factory.
- Remove the play_mdbook command and associated tests.
- Add play_publisher command and tests for publishing books.
- Update the repository cache to use a reference to the redis client.

Co-authored-by: mahmmoud.hassanein <mahmmoud.hassanein@gmail.com>

lib/develop/gittools/repository_cache.v

@@ -3,7 +3,7 @@ module gittools
 import json
 import freeflowuniverse.herolib.core.redisclient
 
-fn redis_get() redisclient.Redis {
+fn redis_get() &redisclient.Redis {
 	mut redis_client := redisclient.core_get() or { panic(err) }
 	return redis_client
 }