Place .problem, .subprob and .method into environment consistently

Since this is a common need, it is being functionalized to ensure consistency.

Usage

fill_prob_subprob_method(
  xpdb,
  .problem,
  .subprob,
  .method,
  envir = parent.frame()
)

Arguments

xpdb

<xpose_data> or related object

.problem

NULL or missing

.subprob

NULL or missing

.method

NULL or missing

envir

<environment> in which to assign the problem info.