We weren't really translating between location (line and column number)
and source position (character offset) consistently, especially when it
came to inline <script>s. There were also inconsistencies between what
Debugger.getPossibleBreakpoints and Debugger.setBreakpointByUrl would
do.

With this CL, we are now consistently operating under the following
assumptions:

(1) For inline <scripts>s with a //@ sourceURL annotation, we assume
    that the line and column number that comes in via the protocol is
    in terms of the source text of the script.
(2) For inline <script>s without said annotation, we assume that the
    line and column numbers are in terms of the surrounding document.

This is finally aligned with how the DevTools front-end operates.

Fixed: chromium:1319828
Change-Id: I98c4ef04b34a97caf060ff4f32690b135edb6ee6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3610622Reviewed-by: Kim-Anh Tran <kimanh@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Kim-Anh Tran <kimanh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80292}