mathlib

98a9eb25 - feat(analysis/special_functions/trigonometric/angle): more on angles equal or not equal to 0 or π (#16055)

feat(analysis/special_functions/trigonometric/angle): more on angles equal or not equal to 0 or π (#16055) We have various lemmas giving conditions for an angle to equal 0 or π. Add some more such lemmas, plus negated versions of existing lemmas giving conditions for angles not to equal 0 or π.