PolyhedralGeometry: more operators on fans and complexes

[YueRen]

This draft pull request comes from the Leipzig Workshop aims to add the following new operations:

• Scalar * PolyhedralFan and PolyhedralFan * Scalar
• Scalar * PolyhedralComplex and PolyhedralFan * Scalar
• -PolyhedralFan
• -PolyhedralComplex
• Vector + PolyhedralFan and PolyhedralFan + Vector
• Vector + PolyhedralComplex and PolyhedralComplex + Vector

Questions:

1. Do we want these functions? My collaborators and I need it for various reasons:

• negation is useful to construct the negated Bergman fan of a matroid (arises for example here)
• translation is useful to see how the initial ideals of the tropical intersection points vary (relevant for example for this)

(If yes, I will add the relevant operators for Cone, the operators for Polyhedron already exist)

2. Is the implementation okay (in particular, I wasn't 100% sure where to put the functions)?

[codecov]

Codecov Report

Attention: Patch coverage is 67.18750% with 21 lines in your changes missing coverage. Please review.

Project coverage is 84.39%. Comparing base (9627744) to head (2a70b17).

Files with missing lines	Patch %	Lines
...ometry/PolyhedralComplex/standard_constructions.jl	65.85%	14 Missing ⚠️
...alGeometry/PolyhedralFan/standard_constructions.jl	69.56%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4444      +/-   ##
==========================================
- Coverage   84.41%   84.39%   -0.02%     
==========================================
  Files         668      668              
  Lines       88598    88662      +64     
==========================================
+ Hits        74786    74829      +43     
- Misses      13812    13833      +21     

Files with missing lines	Coverage Δ
...alGeometry/PolyhedralFan/standard_constructions.jl	95.48% <69.56%> (-4.52%)	⬇️
...ometry/PolyhedralComplex/standard_constructions.jl	72.54% <65.85%> (-27.46%)	⬇️