Enable create plugin to work with plugin-example projects

[sympatheticmoose]

We provide a number of plugin examples as a way to get started https://github.com/grafana/grafana-plugin-examples

This proposal is to allow users to select a sample project to start from in create-plugin using something like:
npx @grafana/create-plugin@latest --starter=app-basic

Or interactively:

? What type of plugin would you like? (Use arrow keys)
❯ app 
  datasource 
  panel 
? Which starter project do you want to use (https://github.com/grafana/grafana-plugin-examples)
❯ default
  app-basic
  app-with-dashboards
  app-with-backend
  app-with-extensions
  app-with-extension-point

So that they could leverage a richer set of starting points, staying within the create-plugin context and showcasing the examples we have already created

To do this we would need to make the sample projects in some way "scaffoldable" to accept the user input prior to this point.

As an example, unique values for 2 app plugins with backends and CI include:

docker-compose.yaml
- container_name: '${ORG_NAME}-${PLUGIN_NAME}'
go.mod
- module github.com/${ORG_NAME}/${PLUGIN_NAME}
package.json
- name: ${PLUGIN_NAME}
- description: ${DESCRIPTION}
- author: ${ORG_NAME}
pkg > main.go
- (import) github.com/${ORG_NAME}/${PLUGIN_NAME}/pkg/plugin
- (func main) if err := app.Manage("${ORG_NAME}-${PLUGIN_NAME}-${PLUGIN_TYPE}", plugin.NewApp, app.ManageOpts{}); err != nil {
src > plugin.json
- "name": "${PLUGIN_NAME_START_CASE}",
- "id": "${ORG_NAME}-${PLUGIN_NAME}-${PLUGIN_TYPE}"
- "executable": "gpx_${PLUGIN_NAME}"
- "description": "${DESCRIPTION_SENTENCE_CASE}",
-  "name": "{ORG_NAME_SENTENCE_CASE}"

We would also need to identify any incompatibilities between the projects defined in https://github.com/grafana/grafana-plugin-examples and what the tool generates.

Perhaps in future, the plugin examples are just published rendered templates, and we can keep them in date with npx @grafana/create-plugin@latest update