Support installing script files without shebang

This is currently failing, but I think we can make it work.

$ echo '(println "Hello world")' > foo.clj

$ bbin install foo.clj
{:coords
 {:bbin/url
  "file:///Users/rads/src/bbin/foo.clj"}}

$ foo
/Users/rads/.local/bin/foo: line 1: println: command not found
/Users/rads/.local/bin/foo: line 4: syntax error near unexpected token `;'
/Users/rads/.local/bin/foo: line 4: `; :bbin/start'

babashka / bbin

Support installing script files without shebang #43