[public api] Implement GetOwnerToken rpc

[andrew-farries]

Description

Implement the GetOwnerToken public API RPC.

Related Issue(s)

Closes #9923

How to test

1. Obtain a stable preview environment like the one for this branch (https://af-impleme89b9aedbc7.preview.gitpod-dev.com/workspaces) (could try to use main.preview.gitpod-dev.com but it gets reset all the time).

2. Run the public API, proxying the server JSON RPC API from the preview branch:

cd components/public-api-server
go run . --gitpod-api-url wss://af-impleme89b9aedbc7.preview.gitpod-dev.com/api/v1

3. Start a workspace on the preview env.

4. Run gpctl against the public API to get the owner token for the workspace we just started:

cd dev/gpctl
go run . api --address localhost:9501 --insecure --token $TOKEN workspaces ownertoken --id $WORKSPACE_ID

where $TOKEN is obtained by running:

await window._gp.gitpodService.server.generateNewGitpodToken({ type: 1, scopes: ["function:getGitpodTokenScopes",
	"function:getWorkspace",
	"function:getWorkspaces",
        "function:getOwnerToken",
	"function:listenForWorkspaceInstanceUpdates",
	"resource:default",]})

in the preview environment web console and $WORKSPACE_ID is the id of the workspace we started in step 3.

The command should return the owner token for the workspace running in the preview environment:

{"token":"O-8bE5VSR6a7G_LVNF.JMEv76iylSKOr"}

Release Notes

Implement `GetOwnerToken` rpc on the public api

Documentation

None