feat(ws): add frontend hooks to call create WS backend

[YosiElias]

Implement call to backend to create workspace as part of #57

Tested with this field & data (according to the readme of backend):

    {
    data: {
      name: 'dora',
      paused: false,
      defer_updates: false,
      kind: 'jupyterlab',
      pod_template: {
        pod_metadata: {
          labels: {
            app: 'dora',
          },
          annotations: {
            app: 'dora',
          },
        },
        volumes: {
          home: 'workspace-home-bella',
          data: [
            {
              pvc_name: 'workspace-data-bella',
              mount_path: '/data/my-data',
              read_only: false,
            },
          ],
        },
        options: {
          image_config: 'jupyterlab_scipy_190',
          pod_config: 'tiny_cpu',
        },
      },
    },
  }

[google-oss-prow]

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[ederign]

/assign @paulovmr

[paulovmr]

Hi @YosiElias , could you please rebase this PR after the API changes? Thanks!

[senanz]

/assign

[senanz]

@paulovmr - PR rebased

[paulovmr]

/ok-to-test

[paulovmr]

The JSON field names were changed to camelCase in this PR: #214

Please consider adding this type in the workspaces/frontend/src/shared/types.ts file, with the name WorkspacePodTemplate, and use it in the podTemplate field of the Workspace type.

[paulovmr]

This was changed to camelCase as well.