Feature request: filter by file glob with helm-projectile-grep

[chasecaleb]

Expected behavior

It would be nice to be able to specify a file glob to restrict what files helm-projectile-grep searches, e.g. "*.md" to search only through markdown doc files. It looks like projectile-grep supports this already, according to its docstring:

  "Perform rgrep in the project.

With a prefix ARG asks for files (globbing-aware) which to grep in.
With prefix ARG of `-' (such as `M--'), default the files (without prompt),
to `projectile-grep-default-files'.

With REGEXP given, don't query the user for a regexp."

Actual behavior

Prefix arg is ignored

Environment & version information

• helm-projectile version: 58123f1 (current master as of today)
• helm version (in helm-pkg.el): emacs-helm/helm@2c6839f3, which has 3.8.0 in helm-pkg.el
• projectile version (M-x projectile-version): bbatsov/projectile@87f6078, which has projectile-version of 2.4.0.
• Emacs version (M-x emacs-version): 27.2
• OS: Arch Linux