This is a first step for simplifying the channel state and introducing
new unfunded channel types that hold similar state before being promoted
to funded channels.

Essentially, we want the outer `Channel` type (and upcoming channel types)
to wrap the context so we can apply typestate patterns to the that wrapper
while also deduplicating code for common state and other internal fields.

… fns

This is one of a series of commits to make sure methods are moved by
chunks so they are easily reviewable in diffs. Unfortunately they are
not purely move-only as fields need to be updated for things to
compile, but these should be quite clear.

This is one of a series of commits to make sure methods are moved by
chunks so they are easily reviewable in diffs. Unfortunately they are
not purely move-only as fields need to be updated for things to
compile, but these should be quite clear.

This commit also uses these methods through the `context` field where
needed for compilation and tests to pass due to the above change.

… impl

This is one of a series of commits to make sure methods are moved by
chunks so they are easily reviewable in diffs. Unfortunately they are
not purely move-only as fields need to be updated for things to
compile, but these should be quite clear.

This commit also uses the `context` field where needed for compilation
and tests to pass due to the above change.

This is one of a series of commits to make sure methods are moved by
chunks so they are easily reviewable in diffs. Unfortunately they are
not purely move-only as fields need to be updated for things to
compile, but these should be quite clear.

This commit also uses the `context` field where needed for compilation
and tests to pass due to the above change.

This is one of a series of commits to make sure methods are moved by
chunks so they are easily reviewable in diffs. Unfortunately they are
not purely move-only as fields need to be updated for things to
compile, but these should be quite clear.

This commit also uses the `context` field where needed for compilation
and tests to pass due to the above change.

This is one of a series of commits to make sure methods are moved by
chunks so they are easily reviewable in diffs. Unfortunately they are
not purely move-only as fields to be updated for things to
compile, but these should be quite clear.

This commit also uses the `context` field where needed for compilation
and tests to pass due to the above change.

f s/tarcontext.get_/target_/

To reduce interleaving in commits, we introduce a `context` variable
in methods to be moved in upcoming commits so there is minimal change
with the moves.

… impl

…el_context`

This rename and refactor is so that we can get channel details from a
`ChannelContext` which is a common object to all channels.

…ext`

This commit also adds two new maps to `PeerState` for keeping track
of `OutboundV1Channel`s and `InboundV1Channel`s so that further
commits are a bit easier to review.