feat(enr): added enr builder waku capabilities extension

[LNSD]

This PR introduces the Waku ENR capabilities field extension to the EnrBuilder type.

• Added the EnrBuilder Waku node capabilities extension.
• Added tests covering this functionality.

[alrevuelta]

lgtm! left a non blocking comment.

[alrevuelta]

just an opinion. I generally prefer one function rather than multiple ones. less code to read, more simple and clearer. not sure I see the value of having all three.

Isn't this too low level? Cool thing about the builder is abstracting away all this
withWakuCapabilities(..., caps: CapabilitiesBitfield))

Both are very similar.
withWakuCapabilities(Relay, Store)
withWakuCapabilities(@[Relay, Store])

tldr: I would just leave withWakuCapabilities(@[Relay, Store])

[LNSD]

Different proc signatures, cover different use cases.

At first sight, you can see it as too low level, for example. But IIRC, this is the exact API we need to create an ENR in the Waku discv5 module. A similar thing happens with the multiple capabilities methods: it is not the same to pass a seq[T] than a varargs[T]. You can convert easily a varargs instance into a sequence, but the opposite has some compilation-time implications. The varargs type can be understood as an array of known sizes at compile time, on the other hand, the sequence type is a dynamic size (pointer, length, and capacity backed) list of elements.

[jm-clius]

LGTM, thanks!