ARI: Correct error codes for bridge operations

This patch adds error checking to ARI bridge operations, when
adding/removing channels to/from bridges.

In general, the error codes fall out as follows:
 * Bridge not found - 404 Not Found
 * Bridge not in Stasis - 409 Conflict
 * Channel not found - 400 Bad Request
 * Channel not in Stasis - 422 Unprocessable Entity
 * Channel not in this bridge (on remove) - 422 Unprocessable Entity

(closes issue ASTERISK-22036)
Review: https://reviewboard.asterisk.org/r/2769/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@397565 65c4cc65-6c06-0410-ace0-fbb531ad65f3

rest-api/api-docs/bridges.json

@@ -130,6 +130,10 @@
 						}
 					],
 					"errorResponses": [
+						{
+							"code": 400,
+							"reason": "Channel not found"
+						},
 						{
 							"code": 404,
 							"reason": "Bridge not found"
@@ -140,7 +144,7 @@
 						},
 						{
 							"code": 422,
-							"reason": "Channel not found, or not in Stasis application"
+							"reason": "Channel not in Stasis application"
 						}
 					]
 				}
@@ -172,6 +176,24 @@
 							"allowMultiple": true,
 							"dataType": "string"
 						}
+					],
+					"errorResponses": [
+						{
+							"code": 400,
+							"reason": "Channel not found"
+						},
+						{
+							"code": 404,
+							"reason": "Bridge not found"
+						},
+						{
+							"code": 409,
+							"reason": "Bridge not in Stasis application"
+						},
+						{
+							"code": 422,
+							"reason": "Channel not in this bridge"
+						}
 					]
 				}
 			]