Move plugin conditions from code into plugin metadata

[martinheidegger]

The current plugin mechanism utilizes conditionals like if (handleMessages) to determine which plugins need to be loaded and which do not.

Example:

mycloud/src/in-house-bot/index.ts

Lines 700 to 702 in d86ae91

	if (ONFIDO_RELATED_EVENTS.includes(event) && plugins.onfido && plugins.onfido.apiKey) {
	attachPlugin({ name: 'onfido' })
	}

This makes two things difficult.

1. When modifying a plugin we can not easily see under which conditions the plugin is executed.
2. It is difficult to determine before the plugins get loaded which plugins will be necessary for certain event. This is of note as we want to load plugins dynamically and need to know this in advance, without the plugins themselves being loaded.

To change this I am planning to turn current conditional plugin loading into a meta-data that can be evaluated non-sequentially). For example, this:

mycloud/src/in-house-bot/index.ts

Lines 792 to 799 in d86ae91

	if (
	handleMessages ||
	runAsyncHandlers ||
	event.startsWith('deployment:') ||
	event === LambdaEvents.COMMAND ||
	event === LambdaEvents.SCHEDULER
	) {
	attachPlugin({ name: 'deployment', requiresConf: false })

would be turned into configuration like below:

{
  name: 'deployment',
  visible: true, // To show the plugin in the tradle plugins dialog
  requiresConf: false, // Configuration required for the plugin to be loaded
  hooks: [{
    condition: { isTradle: true }, // we put currently distributed "conditions" into a single object
    events: [
      'message', // on every event of type 'message'
      'resourcestream',
      'deployment:*', // to support .startsWith(...) we need to support patterns
      'command',
      'scheduler'
    ]
  }]
}

This data format externally defined plugins can provide this data-structure as part of the package.json.