Provide a way to create a new extension using a template

[wbachnik]

In order to make extension creation simple for newcomers we should provide a way to initialize extension project with a complete and already working extension template. For example: dt extension init snmp would create all the files and directories required for a working SNMP-based extension, which in the most basic use case requires user to only add metrics specific to her device (and maybe replace/remove metrics added with the template). Of course such command should be available for all supported data sources.

My idea is to create a separate repository within the dynatrace-oss organization that would host extension templates (in directories named after data source labels). Those could be integrated with dt-cli during build time or (preferably, in my opinion) downloaded on demand when dt extension <data source> command is invoked.

The dt extension init <data source> command should take additional parameters that would allow filling in extension.yaml with required metadata, like author or version number.

Further enhancement: Include project files for VSCode or other editors/IDEs when generating the extension structure.

[vduseev]

Closing because this functionality is now a part of the dt-sdk