Rename definition to pipeline, endpoint to connection (#7586)

* First pass of renaming and string tweaks

* Final tweaks

* String tweaks

Tasks/AppCenterDistributeV1/Strings/resources.resjson/en-US/resources.resjson

@@ -5,8 +5,8 @@
   "loc.instanceNameFormat": "Deploy $(app) to Visual Studio App Center",
   "loc.releaseNotes": "Provide commit details to distribution API for additional context.",
   "loc.group.displayName.symbols": "Symbols",
-  "loc.input.label.serverEndpoint": "App Center connection",
-  "loc.input.help.serverEndpoint": "Select the service endpoint for your Visual Studio App Center connection. To create one, click the Manage link and create a new service endpoint.",
+  "loc.input.label.serverEndpoint": "App Center service connection",
+  "loc.input.help.serverEndpoint": "Select the service connection for Visual Studio App Center. To create one, click the Manage link and create a new service connection.",
   "loc.input.label.appSlug": "App slug",
   "loc.input.help.appSlug": "The app slug is in the format of **{username}/{app_identifier}**.  To locate **{username}** and **{app_identifier}** for an app, click on its name from https://appcenter.ms/apps, and the resulting URL is in the format of [https://appcenter.ms/users/<b>{username}</b>/apps/<b>{app_identifier}</b>](https://appcenter.ms/users/{username}/apps/{app_identifier}). If you are using orgs, the app slug is of the format **{orgname}/{app_identifier}**.",
   "loc.input.label.app": "Binary file path",
@@ -32,7 +32,7 @@
   "loc.messages.CannotDecodeEndpoint": "Could not decode the endpoint.",
   "loc.messages.NoResponseFromServer": "No response from server.",
   "loc.messages.FailedToUploadFile": "Failed to complete file upload.",
-  "loc.messages.NoApiTokenFound": "No API token found on Visual Studio App Center connection.",
+  "loc.messages.NoApiTokenFound": "No API token found on the Visual Studio App Center service connection.",
   "loc.messages.Succeeded": "App Center Distribute task succeeded",
   "loc.messages.CannotFindAnyFile": "Cannot find any file based on %s.",
   "loc.messages.FoundMultipleFiles": "Found multiple files matching %s.",