Default name and modifiers properties for modifiers

[BENR0]

Feature Request

Even though manual application of a modifier for example the SunZenithCorrector might be an unusual use case, the name and modifiers init kwargs should be set by default for modifiers (normally these get set during loading from the yaml configs) . This would make attributes more consistent.

Currently this has to be set by the user like so:

from satpy.modifiers import SunZenithCorrector

szen_corrector = SunZenithCorrector(name="szen_corrector", modifiers=("sunz_corrected",))

Ideally the user can just initialize it like this (also because the above behaviour is not documented)

szen_corrector = SunZenithCorrector()

Describe any changes to existing user workflow
As far as I can see there are not changes.

[djhoese]

Sounds good to me. I'm sure there will be annoying edge cases, but this seems like it would be going in the right direction. I also assume that modifiers[0] should be equal to the value of name right? That should maybe be checked in the __init__.

[BENR0]

Ok I will make a PR then. Should be straight forward I think.