Fix inline and docblock comments in core that uses "Url" in sentences

Problem/Motivation

This issue is to coordinate all the steps in order to discuss and potentially fix "Url" in sentences (which may in some cases refer to a Drupal\Core\Url object).

Steps to reproduce

Proposed resolution

List uses in core with sentences using "Url" in a sentence (without its namespace) to "URL".

For docblocks:

grep -r " Url" * | grep "\* " | grep -v "vendor" | grep -v "node_modules"

For inline comments

grep -r " Url" * | grep "// " | grep -v "vendor" | grep -v "node_modules"

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet