Relative deployment path support

[lajoiemedia]

When parcel is launched with the option parcel build --public-url ./ in order to build for deployment outside the root of the server, static-rendered routes no longer reference their resources correctly.

For my directory structure

• build/
  • index.html
  • script_hash.js
  • myroute/
    • index.html

build/index.html will have a script tag that looks like:
<script src="script_hash.js"></script>
(Which is good)

BUT

build/myroute/index.html will also have a script tag which looks like:
<script src="script_hash.js"></script>
(Which will fail since the script is not in the same subdir)

The same applies to other resources (CSS, ico, etc.)