Use initial query as pre-filter expression over mark names if provided

[bmundt6]

With this update, an additional pass of fzf in filter mode runs on the marks list, fuzzy-matching field 1 (mark name) against the strings provided on the command-line, if any. Then, the scope of the interactive search is limited only to bookmarks matching the query, and the initial query string is always empty.

This pairs well with #55 and with command-line TAB completion, since any string provided in the initial fzm call is always understood to be some part of a mark name, not a path component. A basic example use case: suppose I have marks foo and foobar among others and I begin typing jump fo. Then I hit TAB, and the command-line becomes jump foo. Then, I hit enter, and fzm shows me only two options to select from, foo and foobar, no matter what path components in other marks might also match the string foo.