Add analyzer and fixer for (AK1002) Must not await GracefulStop() inside ReceiveAsync

[Arkatufus]

Fixes #49

Changes

• Add new rule AK1002
• Add analyzer
• Add fixer

Converts

ReceiveAsync<string>(async str => {
    await Context.Self.GracefulStop(TimeSpan.FromSeconds(3));
});

to

ReceiveAsync<string>(async str => {
    _ = Context.Self.GracefulStop(TimeSpan.FromSeconds(3));
});

Converts

ReceiveAsync<string>(async str => await Context.Self.GracefulStop(TimeSpan.FromSeconds(3)));

to

ReceiveAsync<string>(async str => _ = Context.Self.GracefulStop(TimeSpan.FromSeconds(3)));

[Aaronontheweb]

Only question I have is on the code fix - see comments

[Aaronontheweb]

LGTM - this might be a pretty useful thing to have for some other analysis rules in the future too.

[Aaronontheweb]

LGTM

[Aaronontheweb]

LGTM