feat: initialize new projects from example as template

[HipsterBrown]

See https://github.com/HipsterBrown/xs-dev/issues/32#issuecomment-1080937811 and https://github.com/HipsterBrown/xs-dev/issues/32#issuecomment-1081009895 for more details.

Example usage:

xs-dev init my-mqtt --example mqttbasic
Generating Moddable project "my-mqtt" from mqttbasic example

Allow for selecting example project base:

xs-dev init my-project --example

Display subset of matching examples if direct match is not found:

xs-dev init my-project --example http