[Server] Add "ping" verb to "connections" REST API in support of ad hoc connectivity checks

Current Behavior

Run a connectivity test to verify the health of any connection by clicking on the connection chip. A quick connectivity test will run and inform you of Meshery’s ability to communicate with that connection. You will be notified of the connection status in a toast notification. You can also verify any other connection between Meshery and either its components (like Meshery Adapters) or other managed infrastructure by clicking on any of the connection chips. When clicked, a chip will perform an ad-hoc connectivity test.

https://github.com/meshery/meshery/assets/7570704/098d0b3c-2620-4bf5-a1a9-1bd5424e5438

Desired Behavior

This behavior should be true for every chip type. It is not currently available to all chips, but is only available to Kubernetes and Meshery Adapter chips.

https://github.com/meshery/meshery/assets/7570704/d6cc4642-c598-4858-b1f2-1adb22717448

1. Support Meshery connection ad hoc connectivity tests.
2. Support GitHub connection ad hoc connectivity tests.

Implementation

1. Follow the same approach as the endpoint handler /api/system/kubernetes/ping?connection_id={id}. See https://docs.meshery.io/reference/rest-apis#api-system-kubernetes-ping-connection_id-id.

Acceptance Tests

1. Upon click of any type of connection chip, an ad hoc connectivity test will be sent from one Meshery Server to the specific connection.
2. A toast notification will display success or failure with details of the name and hostname (address) of the connection.

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