GSoC Week 5

This week, more improvements to Limit.doit were made.

floor and ceiling were not handled by the leading term block due to bugs in their functions. These bugs were mainly related to improper direction handling. These were fixed and hence there is no longer a need to enter the Gruntz limit calculations.

After these changes, many heuristics being used in Limit.doit before the call to gruntz were removed.

There was also a bug in besselj._eval_as_leading_term - a factor of gamma(nu + 1) was missing. This factor was added, and hence sympy/sympy#21701 was fixed.

sin and cos leading term methods no longer return the function itself at real infinites, instead they return AccumBounds(-1, 1). Ei, Ci, Shi, Chi leading term methods were added.

sinh and cosh leading term methods were also improved, to remove the call of contains and handle more cases.

A PR was opened with all these changes - #21731. Next week would be dedicated to firstly addressing the review comments of this PR, and then proceeding to add more special function leading term methods.