QuadFormAndIsom: fixes and a new feature

[StevellM]

Fixes:

• Last fixes on enumeration of finite isometries
• Fixes on Nikulin's primitive embeddings
• Broaden _glue_stabilizers to avoid duplicate code
• Correct obvious typos

New feature:

• Enumeration of isometries of infinite order with irreducible minimal polynomial

[codecov]

Codecov Report

Merging #3394 (c6d9624) into master (56b8182) will decrease coverage by 0.12%.
Report is 6 commits behind head on master.
The diff coverage is 68.47%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3394      +/-   ##
==========================================
- Coverage   82.08%   81.96%   -0.12%     
==========================================
  Files         557      557              
  Lines       73971    74034      +63     
==========================================
- Hits        60716    60685      -31     
- Misses      13255    13349      +94     

Files	Coverage Δ
...ntal/QuadFormAndIsom/src/lattices_with_isometry.jl	99.44% <100.00%> (-0.04%)	⬇️
...mental/QuadFormAndIsom/src/spaces_with_isometry.jl	98.48% <ø> (ø)
experimental/QuadFormAndIsom/test/runtests.jl	100.00% <100.00%> (ø)
experimental/QuadFormAndIsom/src/enumeration.jl	96.62% <96.55%> (+1.81%)	⬆️
experimental/QuadFormAndIsom/src/embeddings.jl	96.38% <88.88%> (-0.24%)	⬇️
.../QuadFormAndIsom/src/hermitian_miranda_morrison.jl	47.28% <12.79%> (-25.43%)	⬇️

... and 2 files with indirect coverage changes

[simonbrandhorst]

please document what this function computes (even though it is internal)