v1.2: Improve background task handling (#116)

• introduce “task manager” to improve synchronization of data loading and reconstruction tasks; implement blocking option for diffraction data loading and reconstruction tasks
• several breaking API changes: renamed scan -> probe positions based on user feedback, add option to disable diffraction pattern processing
• implement reconstruction progress monitoring
• fix bad pixels handling and add documentation for good/bad pixel masks
• simplify behavior of crop center editing widgets
• closing diffraction dataset clears visualization
• rework stxm analysis dialog to stxm object builder
• improve object fourier analysis dialog and promote from developer mode
• extract globus integration from workflow module
• rename ptychoshelves readers -> fold_slice readers; fix loss value loading
• change default hdf5 file writer compression method to lzf
• fix fresnel zone plate probe builder for rectangular probes
• display current object and probe pixel sizes in GUI
• remove tike integration
• add convert-to-ptychodus script for translating prepared datasets to ptychodus file format
• update ptychouds-bdp script and batch mode actions to use standard directory layout
• standardize argument naming across scripts
• add convert-to-ptychodus and ptychodus-bdp to project scripts