Recognize file-header pragmas in GHCi (#21507)
See #21507. This MR causes GHCi to recognize and apply any file-header pragmas it sees when running a line in GHCi. Also related to #20473 (closed).
See #21507. This MR causes GHCi to recognize and apply any file-header pragmas it sees when running a line in GHCi. Also related to #20473 (closed).