[focus-without-user-activation] Add pseudo algorithm and examples

[ffiori]

Expand the explainer with some clarifications to the focus workflow.

• Add pseudo algorithm to describe how the policy integrates with the focusing process.
• Add a table in the Appendix to list some examples of how this would work.
• Remove 'The Extra Mile' section since it's already been discussed that this is not a viable solution to the problem (as described in the 'Alternative solutions' section).

[ffiori]

Thanks for the review, Dan.

@clelland, could you PTAL? Thanks!

[ffiori]

@clelland friendly ping on this PR, I'd appreciate if you could take a look when you have some time :)