Integrate Python GAPIC Microgenerator in googleapis. This PR uses using documentai as an example. Depends on googleapis/gapic-generator-python#402

PiperOrigin-RevId: 309824146

Source-Author: Google APIs <[email protected]>
Source-Date: Mon May 4 15:06:44 2020 -0700
Source-Repo: googleapis/googleapis
Source-Sha: e0f9d9e1f9de890db765be46f45ca8490723e3eb
Source-Link: googleapis/googleapis@e0f9d9e

Author: yoshi-automation

google/cloud/trace_v1/proto/trace_pb2.py

@@ -3,23 +3,23 @@
     {
       "git": {
         "name": ".",
-        "remote": "git@github.com:googleapis/python-trace",
-        "sha": "821cc6d7f74d731753ead631131cb5bf21b633c1"
+        "remote": "https://github.com/googleapis/python-trace.git",
+        "sha": "74df351491d4e52efa728a2c42b3c5b6ea158812"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "756b174de4a122461993c1c583345533d819936d",
-        "internalRef": "308824110"
+        "sha": "e0f9d9e1f9de890db765be46f45ca8490723e3eb",
+        "internalRef": "309824146"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "01b6f23d24b27878b48667ce597876d66b59780e"
+        "sha": "04cb397eb7590ea1e6c10a39fca3d8fe0fb3d256"
       }
     }
   ],