Adds api for library usage

[codefromthecrypt]

This is a sketch. A real impl will need to test things, similar to our e2e test. Particularly there could be some tricky things for example, how to signal close since the envoy run will block the calling thread. This is mainly to show that the api approach should be precise and only expose top-level concepts that relevant to import.

Fixes: #433

[codefromthecrypt]

added notes on how to proceed

[codefromthecrypt]

protip. we have some infrastructure that allows unit testing w/o remote download deps

something like..

homeDir := t.TempDir()
envoyVersion := version.LastKnownEnvoy
versionsServer := test.RequireEnvoyVersionsTestServer(t, envoyVersion)
defer versionsServer.Close()
envoyVersionsURL := versionsServer.URL + "/envoy-versions.json"
out := new(bytes.Buffer)

... now use em

[arkodg]

looks like the value in https://github.com/tetratelabs/func-e/blob/master/internal/version/last_known_envoy.txt is causing the CI to fail

[codefromthecrypt]

seems thing haven't been maintained in a while. I ran the 1.23.1 tag on archive-envoy and then raised this to move to it #435

[arkodg]

getting this error on windows

--- FAIL: TestRun (5.79s)
[162](https://github.com/tetratelabs/func-e/actions/runs/3364779609/jobs/5579526006#step:6:163)
    testing.go:1090: TempDir RemoveAll cleanup: remove C:\Users\RUNNER~1\AppData\Local\Temp\TestRun607085353\001\runs\1667250752759535200\stderr.log: The process cannot access the file because it is being used by another process.

@codefromthecrypt any idea why that might be happening ?

[codefromthecrypt]

added some thoughts, noting that windows concerns are a big reason why the e2e directory has some custom runner code, and also that we have things like moreos

[RoeiGanor]

Hey !
I love the idea of the this pull request and I would like to know what is the status of this PR. Is it possible to use funce in this method and if so, how?

[arkodg]

Hey @mathetake can you ptal ( since @codefromthecrypt is a co-author ) ?

[codefromthecrypt]

Since it isn't obvious to everyone why I closed this. Here's why.

This repo has no stale bot. Things dead without impact for several months should be closed. Anyone who is motivated and can do a decent job in execution can carry it forward. However, I'm not going to hold that up and have closed all PRs on all repos that have been dead for periods of 6 months or longer.