Tasks page refactor

[WithoutPants]

Resolves #908

Moves the Scan, Generate and Clean tasks behind dialogs and reorders the tasks page:

Folder selection is integrated in the dialogs if the selective method was available prior.

Note that the preview generation settings and the overwrite flag have been rolled into the generate dialog so that they are available both on the tasks page and from scene selection.

Todo:

• save defaults for all tasks

The following should be implemented after this PR is merged:

• add path selection for clean per [Feature] Selective Clean #1074
• add path selection for generate
• provide force parameter for transcodes per [Bug Report] Transcode file formats doesn't line up exactly #1683

[WithoutPants]

Restyled based on feedback.

Tasks with a separate ellipsis button will run the task using the default settings if the main button is clicked, and will open the dialog if the ellipsis button is clicked. Where there is no defaults set in the configuration, the dialog will open regardless of which button is clicked. A toast message now appears saving defaults indicating that the default settings will be used when clicking the main button.

Added default setting support for scan, auto tag and generate tasks.

[WithoutPants]

Reverted most of the re-styling changes. Separated ellipsis buttons remain, as well as grouping the tasks.

[bnkai]

• The default settings while being saved correctly in the config file dont seem to get passed back to the UI.
  For example using the scan
  
  Select some options and save
  
  Close the dialog and reopen and you get the first image again

• The paths for the selective scan are not sent to the backend

[WithoutPants]

Bloody config refactor biting me again. Should be fixed now.

[bnkai]

• The
  The paths for the selective scan are not sent to the backend
  issue is still present.
  Click on a scan/autotag task for example. Select and add a small subdirectory. Click scan/autotag/.... The scanning/taggins goes through all files since the paths are not sent via the graphql request even though they are displayed in the UI dialog

• The default config settings now work ok

• Another minor UI issue
  If you untick something in the autotag dialog
  
  You can't tick it back

[WithoutPants]

Sorry, didn't read the entire list. The other issues should now be addressed.