META: slsqp optimizer

[dschmitz89]

Hi all,

after looking at the long list of scipy.optimize issues I thought it was a good idea to generate a separate tracking issue for the slsqp optimizer. Why? There is almost a dozen related issues and slsqp is currently being rewritten in Python in #19121. So we could see if the new implementation potentially closes some of them.

CC @ilayn

#3816 list for the args argument needs to be coerced into tuple
#6689 : proposes to use nlopt's implememtation. Can definitely be closed once #19121 is merged.
#7519
#15179
#14915
#14394 asks to return Lagrange multipliers
#10416 slsqp does not work for more than 32bit decision variables
#8065 slsqp converges to maximum, not minimum
#19362 The warning emitted is not helpful

Undocumented parameter acc
#3824
#7518