Implement Alternating Linear Minimization

[JannisHal]

Implemented Alternating Linear Minimization framework with Block Coordinate FW corresponding tests and examples.

[codecov]

Codecov Report

Patch coverage: 95.48% and project coverage change: -0.51% ⚠️

Comparison is base (4468c8f) 87.67% compared to head (9df69b2) 87.17%.
Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #407      +/-   ##
==========================================
- Coverage   87.67%   87.17%   -0.51%     
==========================================
  Files          18       20       +2     
  Lines        2239     2370     +131     
==========================================
+ Hits         1963     2066     +103     
- Misses        276      304      +28     

Files Changed	Coverage Δ
src/FrankWolfe.jl	100.00% <ø> (ø)
src/block_coordinate_algorithms.jl	94.87% <94.87%> (ø)
src/alm.jl	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[matbesancon]

For documentation, there should be a new documentation page placed in docs/src/reference/
probably 5_intersection_problems.md, with the same layout as the other ones