[FTheoryTools] Added additional zero section functionality

[emikelsons]

• Added zero_section_index attribute, that was mentioned in [FTheoryTools] Compute all well-quantized and vertical G4-fluxes #4286
• Corrected zero sections, that were previously incorrectly specified for some models
• Added information about zero section classes for the toric hypersurface models

[emikelsons]

cc @HereAround @apturner

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.52%. Comparing base (3e670f7) to head (bf8cc4d).
Report is 5 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4343   +/-   ##
=======================================
  Coverage   84.52%   84.52%           
=======================================
  Files         645      645           
  Lines       85706    85714    +8     
=======================================
+ Hits        72440    72447    +7     
- Misses      13266    13267    +1     

Files with missing lines	Coverage Δ
...heoryTools/src/AbstractFTheoryModels/attributes.jl	99.60% <100.00%> (+<0.01%)	⬆️
.../FTheoryTools/src/AbstractFTheoryModels/methods.jl	78.33% <100.00%> (+0.06%)	⬆️

... and 1 file with indirect coverage changes

[HereAround]

Thank you for working on this @emikelsons . Looks good.

Since #4286 has been merged, we should use the zero_section_index in this functionality. Please look into this @emikelsons (in a separate PR). Thank you!