Update GNU Radio flowcharts to version 3.8

Update the GNU Radio flowcharts from version 3.7 to version 3.8. This includes the following changes:

• Adding callsigns for Beesat 9 and TechnoSat.
• Update the OOT modules to GNU radio 3.8.
• Update the xml block files to yml.
• Updating of the format of the grc files.
• Replacing the blk_valve with a Selector as the valve was deprecated in version 3.7 and removed in version 3.8.
• Replacing the GUI components with QT components. This is required as the old components were removed. As much as possible a like for like replacement has been made.

NOTE: For ease of review I have separated the commits for this MR but as they will not work separately they will need to be squashed before merging.