Standardize platform name and sensor attributes/properties in readers

[BENR0]

Feature Request

Is your feature request related to a problem? Please describe.
Sometimes platform_name and/or sensor attributes are missing in DataArrays returned by readers (e.g. #2993)

Describe the solution you'd like
Every reader should put platform_name and sensor as attributes in DataArrays. Some readers (e.g. FCI even have properties regarding these values see:

satpy/satpy/readers/fci_l2_nc.py

Lines 43 to 51 in c214917

	@property
	def spacecraft_name(self):
	"""Return spacecraft name."""
	return self.nc.attrs["platform"]
	@property
	def sensor_name(self):
	"""Return instrument name."""
	return self.nc.attrs["data_source"]

)

• Ideally the platform_name and sensor attributes would align with the names from https://space.oscar.wmo.int/(satellites/instruments). An open question might be how to handle possible renaming e.g. when switching from commissioning to operational setup (e.g. currently space oscar is listing MTG-I1 which will be renamed to Meteosat-12).
• Should readers also have these values as properties like in the FCI reader currently?

Describe any changes to existing user workflow
Should not directly affect useres