fix(meta): unify http oauth key to small case

Signed-off-by: Jiyong Huang <huangjy@emqx.io>

etc/sinks/rest.json

@@ -206,12 +206,12 @@
       }
     },
     {
-      "name": "oAuth",
+      "name": "oauth",
       "optional": true,
       "control": "list",
       "type": "list_object",
       "hint": {
-        "en_US": "Configure the oAuth authentication flow.",
+        "en_US": "Configure the oauth authentication flow.",
         "zh_CN": "配置 OAuth 验证流程。"
       },
       "label": {

etc/sources/httppull.json

@@ -235,7 +235,7 @@
 			}
 		},
 		{
-			"name": "oAuth",
+			"name": "oauth",
 			"optional": true,
 			"control": "list",
 			"type": "list_object",

etc/sources/httppull.yaml

@@ -23,7 +23,7 @@ default:
   # how to check the response status, by status code or by body
   responseType: code
 #  # Get token
-#  oAuth:
+#  oauth:
 #    # Access token fetch method
 #    access:
 #      # Url to fetch access token, always use POST method
@@ -65,7 +65,7 @@ neuron:
   # how to check the response status
   responseType: code
   # Get token
-  oAuth:
+  oauth:
     # Access token fetch method
     access:
       # Url to fetch access token, always use POST method