Create asset modified cleanup handler

[JackLewis-digirati]

Resolves #430
links WDLS-507

This PR reimplements work done on #841 as well as implementing the work required by the asset modified cleanup handler.

It includes a new appsettings section:

"AssetModifiedSettings": {
  "DryRun": false,
  "EngineRoot": "https://localhost:7014"
},

And

"UpdateNotificationQueueName": "dlcsspinup-update-notification"

DryRun determines whether the application should actually remove files/db entries and is false by default
EngineRoot is used for setting the engine URI, which is used by the cleanup handler to retrieve details encoding presets from engine

Additional changes in this PR includes allowing the cleanup handler to listen to multiple SQS queues and an additional endpoint added to the engine for retrieving a dictionary of presets

UpdateNotificationQueueName details the name of the queue

[donaldgray]

Not worth changing, just an observation, but the fact that these 2 IQueue* dependencies are brought in due to use of IEngineClient doesn't feel right. We should maybe have an IEngineClient for ingesting and another for querying the api.. 🤔