Add 'gate' command

[ono-max]

✗ launchable record build --name 238                                   
Launchable transferred 1 more commit and 0 more files from repository /Users/ono-max/src/github.com/launchableinc/cli
Launchable recorded build 238 to workspace launchableinc/mothership with commits from 1 repository:

| Name   | Path   | HEAD Commit                              |
|--------|--------|------------------------------------------|
| .      | .      | 49662150d584f8ab1e4f0c42aed3b2b933207795 |

Visit https://app.launchableinc.com/organizations/launchableinc/workspaces/mothership/data/builds/304 to view this build and its test sessions

✗ launchable record session --build 238 > session.txt 

✗ launchable record tests --session "$(cat session.txt)" file test-results/*.xml
Launchable recorded tests for build 239 (test session 319) to workspace launchableinc/mothership from 62 files:

|   Files found |   Tests found |   Tests passed |   Tests failed |   Total duration (min) |
|---------------|---------------|----------------|----------------|------------------------|
|            62 |           214 |            213 |              1 |                   0.17 |

Visit https://app.launchableinc.com/organizations/launchableinc/workspaces/mothership/test-sessions/319 to view uploaded test results (or run `launchable inspect tests --test-session-id 319`)

✗ launchable gate --session "$(cat session.txt)"                                
| Status   |   Quarantined (Ignored) |   Actionable Failures |
|----------|-------------------------|-----------------------|
| PASSED   |                       1 |                     0 |

✗ echo $?                                                                       
0