Add FCI L1C reader short and long name metadata

[djhoese]

Adds short_name, long_name, and a longer description for the FCI reader. This is so GUI applications like my SIFT tool can display a "prettier" name for this reader.

[djhoese]

@gerritholl FYI ^

[coveralls]

Coverage increased (+0.01%) to 86.893% when pulling 6e986a0 on djhoese:feature-fci-reader-metadata into 071e34b on pytroll:master.

[codecov]

Codecov Report

Merging #999 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #999      +/-   ##
==========================================
- Coverage   86.89%   86.89%   -0.01%     
==========================================
  Files         181      181              
  Lines       27497    27497              
==========================================
- Hits        23894    23893       -1     
- Misses       3603     3604       +1

Impacted Files	Coverage Δ
satpy/scene.py	90.35% <0%> (-0.18%)	⬇️

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[gerritholl]

As far as I'm concerned we don't need the word "generic". I think it's not meaningful. A generic FCI L1C reader would read both FDHSI and HRFI.

[djhoese]

Ok i reworded it based on the comments here and on slack.

[mraspaud]

LGTM