[BUG] Ignores directories in output filename/sourcemap

[probins]

Describe the bug
If the output filename includes a directory - subdir/output.js - it is ignored, and the file written to the current directory

To Reproduce
Enter subdir/output.js in output file config.

Expected behavior
FIle and sourcemap should be put in subdir.

Desktop (please complete the following information):

• Deno version 1.6.2
• denopack version 0.10.0

Additional context
emitFiles.ts seems to be confusing the dir and file options. dir is for code splitting chunks, and isn't used for single build file. This bit of code needs rewriting.

[probins]

PS I just tested code splitting and multi-file input, and this seems to work nicely.