feat!: add meta field on Waku Message and provide setter and validation interfaces

[fryorcraken]

Ref: #1208

[github-actions]

size-limit report 📦

Path	Size	Loading time (3g)	Running time (snapdragon)	Total time
Waku core	114.66 KB (+0.09% 🔺)	2.3 s (+0.09% 🔺)	3.5 s (+30.26% 🔺)	5.8 s
Waku default setup	366.75 KB (+0.06% 🔺)	7.4 s (+0.06% 🔺)	5.6 s (-14.65% 🔽)	13 s
ECIES encryption	27.9 KB (+0.56% 🔺)	559 ms (+0.56% 🔺)	1.2 s (-27.51% 🔽)	1.8 s
Symmetric encryption	27.91 KB (+0.56% 🔺)	559 ms (+0.56% 🔺)	1.7 s (+7.92% 🔺)	2.2 s
DNS discovery	108.05 KB (0%)	2.2 s (0%)	3.4 s (+16.68% 🔺)	5.5 s
Privacy preserving protocols	114.16 KB (+0.09% 🔺)	2.3 s (+0.09% 🔺)	2.9 s (+28.4% 🔺)	5.2 s
Light protocols	115.92 KB (+0.05% 🔺)	2.4 s (+0.05% 🔺)	2.5 s (-8.41% 🔽)	4.8 s
History retrieval protocols	115.96 KB (+0.07% 🔺)	2.4 s (+0.07% 🔺)	2.1 s (-11.64% 🔽)	4.4 s

[fryorcraken]

Cc @felicio

[fryorcraken]

Note: can be reviewed by patches (first adds encoding, second adds decoding)

[fryorcraken]

The validation interface isMetaValid may be premature. I assumed for some reason that the MUID would be stored in meta and hence message integrity would be checked for a given application/pubsub topic.

Reading waku-org/pm#9 more closely, this is incorrect.

meta is an application specific field. The usage is not yet defined. I believe it's likely to be a signature for Status Communities? Would be keen to have more info on that to know whether isMetaValid is useful as is, should be changed or even removed.

Cc @felicio @LNSD

[weboko]

Looks a bit complicated but good to me!

[fryorcraken]

Superseded by #1238

Will wait to get more context before adding the isMetaValid helper.