Chebyshev polynomial of the first kind (#78196)
Adds:
```Python
chebyshev_polynomial_t(input, n, *, out=None) -> Tensor
```
Chebyshev polynomial of the first kind $T_{n}(\text{input})$.
If $n = 0$, $1$ is returned. If $n = 1$, $\text{input}$ is returned. If $n < 6$ or $|\text{input}| > 1$ the recursion:
$$T_{n + 1}(\text{input}) = 2 \times \text{input} \times T_{n}(\text{input}) - T_{n - 1}(\text{input})$$
is evaluated. Otherwise, the explicit trigonometric formula:
$$T_{n}(\text{input}) = \text{cos}(n \times \text{arccos}(x))$$
is evaluated.
## Derivatives
Recommended $k$-derivative formula with respect to $\text{input}$:
$$2^{-1 + k} \times n \times \Gamma(k) \times C_{-k + n}^{k}(\text{input})$$
where $C$ is the Gegenbauer polynomial.
Recommended $k$-derivative formula with respect to $\text{n}$:
$$\text{arccos}(\text{input})^{k} \times \text{cos}(\frac{k \times \pi}{2} + n \times \text{arccos}(\text{input})).$$
## Example
```Python
x = torch.linspace(-1, 1, 256)
matplotlib.pyplot.plot(x, torch.special.chebyshev_polynomial_t(x, 10))
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78196
Approved by: https://github.com/mruberry
