sup_quant_orc: True quantile value approximation
In koohyun-kwon/HTEBand: Uniform confidence band for heterogenous treatment effects

Calulates the true quantile of the supremum of absolute value of a studentized process by simulation

sup_quant_orc(
  eps.1.mat,
  eps.0.mat,
  w.1.arr,
  w.0.arr,
  omega.1,
  omega.0,
  T.grad.mat,
  level,
  M,
  useloop = TRUE
)

`eps.1.mat`	a `n.1 * M` by `k` matrix of residuals generated from the true distribution, corresponding to the treated observations
`eps.0.mat`	a `n.0 * M` by `k` matrix of residuals generated from the true distribution, corresponding to the treated observations
`w.1.arr`	A `n_1` by `k` by `n.T` dimensional array of weight values corresponding to treated observations
`w.0.arr`	A `n_0` by `k` by `n.T` dimensional array of weight values corresponding to treated observations
`omega.1`	A `n_1` by `k` by `k` array of conditional variance corresponding to treated observations
`omega.0`	A `n_0` by `k` by `k` array of conditional variance corresponding to control observations
`T.grad.mat`	A `n.T` by `k` dimensional gradient matrix of `T_t f` for `t` = 1,..., `n.T`.
`level`	level of quantile
`M`	number of bootstrap simulations
`useloop`	If `TRUE`, the function is implemented by `for` loop over `t` = 1,..., `n.T`; currently only `useloop = TRUE` is implemented.