chore!: change all instances of PubSubTopic to PubsubTopic

[danisharora099]

Follow up to #1653 and #1697 (review)

Followup TODO:

• write a script or shift word-checking library to match patterns (regex) for flagging instead of full words: feat: ability to flag words based on patterns #1704

[github-actions]

size-limit report 📦

Path	Size	Loading time (3g)	Running time (snapdragon)	Total time
Waku core	83.85 KB (-0.01% 🔽)	1.7 s (-0.01% 🔽)	953 ms (+6.43% 🔺)	2.7 s
Waku Simple Light Node	264.26 KB (-0.01% 🔽)	5.3 s (-0.01% 🔽)	1.9 s (-5.5% 🔽)	7.2 s
ECIES encryption	79.46 KB (-0.01% 🔽)	1.6 s (-0.01% 🔽)	1.4 s (+56.22% 🔺)	3 s
Symmetric encryption	79.46 KB (-0.01% 🔽)	1.6 s (-0.01% 🔽)	1.3 s (+5.17% 🔺)	2.8 s
DNS discovery	111.23 KB (0%)	2.3 s (0%)	1.7 s (+30.23% 🔺)	3.9 s
Privacy preserving protocols	131.77 KB (-0.01% 🔽)	2.7 s (-0.01% 🔽)	2 s (+66.83% 🔺)	4.6 s
Light protocols	81.61 KB (-0.01% 🔽)	1.7 s (-0.01% 🔽)	535 ms (-17.39% 🔽)	2.2 s
History retrieval protocols	80.53 KB (-0.01% 🔽)	1.7 s (-0.01% 🔽)	992 ms (+17.54% 🔺)	2.7 s
Deterministic Message Hashing	5.65 KB (0%)	113 ms (0%)	215 ms (-28.68% 🔽)	328 ms

[adklempner]

LGTM 👍