Restructure the way stuff is handled in lnp2p

[Varunram]

Contains name changes, call by value / reference changes, removes unnecessary handler functions and more.

[Varunram]

test fails due to jenkins being down, unrelated to the PR itself.

[delbonis]

Don't mean to frustrate you with all the comments, I just made lnp2p very opinionated because I wanted to make it easier to refactor around.

[Varunram]

Yeah sure, the reason why we have reviews is to debate upon such points. I think we didn't review / discuss upon the refactor PR much before merging, so it makes sense to review them here.

[adiabat]

There are several large binary files in this PR, can you remove them (and maybe rebuild the git commit log to never have them so they're not included in the history)

[Varunram]

should be good now