To support multiple clusters on the same edgecore level.

[click2cloud-ashwin]

What type of PR is this?

• Added a feature:

• Feature details: Extended edgecore clusterd to support multiple clusters on the same edgecore level

                     edgecore (clusterd)
                               /      \
                              /        \
                             /          \
                     cluster A           cluster B

What this PR does / why we need it:

• Earlier clusterd module in edgecore was supporting only single k8s cluster on the same edgecore level.
• This PR resolves the above issue. Now clusterd is configured to support multiple k8s clusters on the same edgecore cluster.
• Also updated setup guide.

Which issue(s) this PR fixes:

Usage: Fixed issue (#82).

Test details:

• Mission deployment to all clusters, to a given cluster, and to selective clusters works fine with the following environment setup.

Case 1: One cloudcore configured with one edgecore where edgecores configured with multiple k8s control planes.

Case 2: One cloudcore configured with multiple edgecores where edgecores configured with multiple k8s control planes.

Case 3: Hierarchical setup of cloudcores and edgecores where each edgecore is configured with multiple k8s control planes.