handle quoted $DATA filename

[kyleam]

Split off from gh-300:

It would take more work to support the quoted values mentioned in NONMEM's docs:

 filename
      Name  of  the  file  containing  the data set.  Must be the first
      option.  If it contains commas, semicolons, or parentheses,  then
      it  must  be  surrounded  by  single quotes ' or double quotes ".
      Filename may also contain  equal  signs  if  it  is  enclosed  in
      quotes.   If  the file is opened by NM-TRAN, filename may contain
      embedded spaces if it is enclosed in quotes, and may  contain  at
      most  80  characters.  If the file is opened by NONMEM, the file-
      name may not contain embedded spaces, and may contain at most  71
      characters.   If  filename is the same as any option of the $DATA
      record, it must be enclosed in quotes.

This commented out data line will also confuse summarys RunDetails parser:

re: https://github.com/metrumresearchgroup/bbi/pull/301#issuecomment-1452057333

[kyleam]

[ probably worth thinking about at the same time ]

The doc also mentions that '*' has a special meaning:

      * may be coded in a problem subsequent to the  first.   This  has
      the  same  effect as omitting the $DATA record (NONMEM is told to
      re-use the previous data set), but allows the CHECKOUT option  to
      be included.  With *, no other option may be included.

There's already a dedicated issue for this at gh-187.