feature request: allow running updatecli() in the current agent

[dduportal]

By default, the updatecli() library spanws an agent based on a container (easier, faster by default).

As a end user, I would want to execute the updatecli commands in the current agent context instead of spawning an agent.

This RFE could be, instead, the same as updatecli/updatecli-action#76, e.g. instead of trying to spawn an agent, the library should check for the updatecli binary (eventually with the specified version) in the current agent, otherwise installing the updatecli binary for the current context.