Added coalignment with context img

[MJWeberg]

Major changes

Added functions and methods required for coalignment of an EISCube or EISMap with a context image

• Added the eispac.fetch_context_image() convenience function for easily downloading a SDO/AIA or SOHO/EIT context image for a given EIS observation
• Added the eispac.coalign_observations() function for coaligning one or more EIS observations with a single reference image. This function can operate on both 'EISCube' and EISMap objects.
• Added EISCube.shift_reference_coord() & EISCube._set_reference_date() methods and updated the EISMap date handling methods (for more consistent behavior)
• These additions finally closes Add function for fixing EIS pointing by coaligning with AIA data. #85

Minor changes

• Cleaned up the metadata in EISCube such that NumPy scalers are properly converted to Python scalers (yet more lingering NumPy 2.0 changes)
• Added xws, yws, ssa, and hlz keys to the output of an EISAsRun catalog search
• Updated and cleaned up some tests