[WIP] Improving solveset univariate Trig inequality

[Shekharrajak]

solveset_univariate_trig_inequality function is added to handle Trigonometric inequality.

Main intention is to get extended solution.

eg.

In [2]: solveset((2*cos(x)+1)/(2*cos(x)-1) > 0, x, S.Reals)
Out[2]:
⎡⎧      π        ⎫  ⎧      π        ⎫⎤
⎢⎨n⋅π - ─ | n ∊ ℤ⎬, ⎨n⋅π + ─ | n ∊ ℤ⎬⎥
⎣⎩      3        ⎭  ⎩      3        ⎭⎦

n [4]: solveset(sin(x) > 1/sqrt(2), x, S.Reals)
Out[4]:
⎛⎧        π        ⎫  ⎧        3⋅π        ⎫⎞
⎜⎨2⋅n⋅π + ─ | n ∊ ℤ⎬, ⎨2⋅n⋅π + ─── | n ∊ ℤ⎬⎟
⎝⎩        4        ⎭  ⎩         4         ⎭⎠

In [15]: solveset(2*cos(x) + sqrt(3) < 0, x, S.Reals)
Out[15]:
⎛⎧        5⋅π        ⎫  ⎧        7⋅π        ⎫⎞
⎜⎨2⋅n⋅π + ─── | n ∊ ℤ⎬, ⎨2⋅n⋅π + ─── | n ∊ ℤ⎬⎟
⎝⎩         6         ⎭  ⎩         6         ⎭⎠

In [16]: solveset_univariate_trig_inequality(tan(x) > 0, x)
Out[16]: 
⎛               ⎧      π        ⎫⎞
⎜{n⋅π | n ∊ ℤ}, ⎨n⋅π + ─ | n ∊ ℤ⎬⎟
⎝               ⎩      2        ⎭⎠

[Shekharrajak]

This PR is not that much good now. It fails some cases. I am trying to improve it. It is inspired from previous solve_univariate_inequality but it seems need changes for trig ineq.

[Shekharrajak]

Original #11188

[Shekharrajak]

Ping @aktech @hargup @kshitij10496 . This is initial code.

[Shekharrajak]

Closing this PR, since @kshitij10496 is working on it.