Enable the use of regex for keywords

[huynle]

The ability to do regex search for text and have it pop up in the :TodoTrouble or :TodoTelescope is very useful for things like Markdown todo lists. In general, the same configuration exists. If you want to make a keyword specifically use regular expression, then assign it to a regular expression. e.g.

      alt = {
        TODO = [=[[*-]\s\[.?\]]=],
        "WIP"
      },

if you want WIP to be a regular expression, then use WIP = [[<my regex here>]]

The overall configuration looks would look something like this.

 keywords = {
    FIX = {
      icon = " ",
      color = "error", -- can be a hex color, or a named color (see below)
      alt = { "FIXME", "BUG", "FIXIT", "FIX", "ISSUE" },
      -- signs = false, -- configure signs for some keywords individually
    },
    TODO = {
      icon = " ",
      color = "info",
      alt = {
        TODO = [=[[*-]\s\[.?\]]=],
        "WIP"
      },
    },
    HACK = { icon = " ", color = "warning" },
    WARN = { icon = " ", color = "warning", alt = { "WARNING", "XXX" } },
    PERF = { icon = " ", alt = { "OPTIM", "PERFORMANCE", "OPTIMIZE" } },
    NOTE = { icon = " ", color = "hint", alt = { "INFO", "HLE", "Q" } },
  },

[github-actions]

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