Some tests involving the directive prologue are invalidated by source
text transformations that insert executable code in the beginning of the
script. Implement a `raw` flag that allows these tests to opt-out of
this transformation. Update the relevant tests to use this flag (and
remove references to globals only available when code is injected).

Update the Python runner accordingly:

- Do not run tests marked as "raw" in strict mode
- Reject invalid test configurations

Update the browser runner accordingly:

- Do not modify the script body of tests marked as "raw"

Update the URLs used by dynamic script loading code according to the new
location of the recently-moved web site scripts.

Some JavaScript source files are only relevant in the context of the
Test262 website. They should not be explicitly included by individual
tests, so their presence in the `harness/` directory alongside "include"
files is misleading.

Move the scripts to a location within the `website/` directory to
better-reflect their intended use. Update the relevant HTML templates
with the new locations.