Manager UI cleanup

With this MR, the Manager receives a UI cleanup:

• Fixed several spacing problems for displaying HFR and guiding parameters
• Removal of space consuming group boxes for the devices
• Introduction of a horizontal slider between the capture part on the left side and mount, focusing and guiding on the right
• The star image for focusing and guiding is only displayed if available

Additionally, the capture counting now consider if the Scheduler is running. There is currently a minor bug due to a concurrency issue when reading the completed captures from the Scheduler. But before I start to introduce a new event that increases the complexity, I decided to live with this bug for a while.

Framework changes

• PlaceholderPath has names for frame types hard coded. I moved it to indicommon.h which seems to be a better place for it.
• Scheduler::currentJob is now publicly accessible. This was necessary to obtain capture countings and job state. This may be reverted if we introduce additional Scheduler events.

Testing

This is mainly a UI cleanup with only a minor risk of regressions. Nevertheless, I would recommend the following steps:

• Start/stop guiding and check, if the guiding graph is displayed.
• Run focusing and check, if the HFR values are displayed correctly.
• Set up several sequences in Capture and let them run. Check, if counting is accurate.
• Execute tests with all frame types
• Set up a Schedule with all variants of completion conditions and check, if counting is accurate.