Support for Compute@Edge Log Tailing

[jaredmorrow]

What does it do?

Adds command: fastly logs tail --service-id=

Output

Because this doesn't run w/o the above mentioned go-fastly, the following is what a log tail session looks like with three requests that just print out a simple message.

fastly/cli [ ./fastly logs tail -s <redacted>

INFO: Managed logging enabled on service <redacted>
stdout | 3fbf507b | Hello from the root path!
stdout | 3fbf507b | 2nd println in this request
stdout | 3fbf507b | 3rd println in this request
stdout | 3fbf507b | 4th println in this request
stdout | 3fbf507b | 5th println in this request
stdout | 3fbf507b | 6th println in this request
stdout | c5035791 | Hello from the root path!
stdout | c5035791 | 2nd println in this request
stdout | c5035791 | 3rd println in this request
stdout | c5035791 | 4th println in this request
stdout | c5035791 | 5th println in this request
stdout | c5035791 | 6th println in this request
stdout | 9154fde8 | Hello from the root path!
stdout | 9154fde8 | 2nd println in this request
stdout | 9154fde8 | 3rd println in this request
stdout | 9154fde8 | 4th println in this request
stdout | 9154fde8 | 5th println in this request
stdout | 9154fde8 | 6th println in this request

[Integralist]

@jaredmorrow thanks for opening this PR. Seems to be a couple of failing tests due to a missing method expected on an interface.

[jaredmorrow]

@Integralist go-fastly v3 required :)

[jaredmorrow]

With go-fastly v3, it is now passing tests.

[Integralist]

@jaredmorrow I'm not all the way done yet. Stopped at the tail_test.go file, and I'll continue on from there will my review shortly (just gotta step away for a bit).

[Integralist]

Here's the second half of my review (although I see you've pushed some changes so maybe some of this has become irrelevant).

[Integralist]

One other final comment, not essential.

[Integralist]

LGTM. I'll merge once the CI tests have passed.