feat(engine, ui): view and edit DLE config for logical jobs via UI (#359)
Description
View and edit DLE config for logical jobs via UI:
- add a mechanism to read and update configuration file using UI
 - validate configuration before applying
 - tests DB source connection by passed parameters
 - reload DLE configs after updating the DLE file
 - store backups of the config file before reloading the configuration (10, by default)
 - run retrieval jobs to create a snapshot after the successful configuration in UI
 - manage state of not configured retrieval (#408 (closed))
 
Related issue
Examples
Checklist
- 
MR description has been reviewed  - 
MR changes are functionally tested  - 
MR does NOT have text changes OR there are text changes and they have been reviewed  - 
MR does NOT have API/CLI changes OR there are API/CLI changes and they have been reviewed  - 
MR does NOT have UI changes OR there are UI changes and they have been reviewed  
Closes #359 (closed)
Edited  by Artyom Kartasov
