At talk for java

[akafredperry]

closes #328
closes #382

- What I did

• New module (not published) for at_talk. This illustrates subscribing to decrypted value events and demonstrates sending notify key updates
• Modifications to the monitoring support in AtClientImpl. The withMonitoring() builder option allows monitoring from construction and avoid having to invoke startMonitor(). MonitorOptions makes all the verb parameters available in Java api.

- How I did it

• Created MonitorOptions.java to model monitor verb parameters.
• Add withMonitoring() to AtClients builder.
• New module at_talk that generates a fatjar (see README)
• AtClientContext can now be simplified, can now use epochMillis (rather than a pause and discard) to prevent tests from "bleeding into each other".

- How to verify it

• Clean install, follow README instructions for at_talk
• Have tested with dart at_talk
• New features have test coverage and all unit and integration tests run as part of this pipeline

- Description for the changelog

feat: at_talk cli

[akafredperry]

this branch is now rebase with trunk

[gkc]

lgtm