lnc: Add a timeout when creating the grpc client with the mailbox

[positiveblue]

Do not hang forever when creating the grpc client with the mailbox.

Also, make sure we use the DefaultStore timeouts every time we call store functions in the package.

Both timeouts are currently set to 10s.

Fix #124

[guggero]

@positiveblue the code looks good, thanks. Maybe we should also bump the LNC dependency to the recently released version v0.3.0 that fixes a couple of issues. That probably will also help increasing the connection stability and reliability.

[positiveblue]

lightning-node-connect version bumped :+1:

I also had to bump the minim go version for compiling the project because LNC needs go 1.21