Improve wording of status report message

Problem/Motivation

If the Toolbar module is installed while the Drupal core Navigation module is also installed, the following message is produced on the Drupal status report:

Toolbar is disabled when the Navigation replacement module is available to the current user. It is recommended to uninstall Toolbar.

I am guessing that if developers have installed the Toolbar contrib module that they really want to use it.

Steps to reproduce

I wasn't able to build this on simplytest.me, and don't have the skills or bandwidth to debug the issue - I'm quality assurance, not a developer. However, if I edit /toolbar/src/Hook/ToolbarRequirements.php, I see that the status message reads:

Toolbar is disabled when the Navigation replacement module is available to the current user. It is recommended to uninstall Toolbar.

Proposed resolution

Change the message text to read:

Toolbar is disabled when the Navigation module is available to the current user. It is recommended to uninstall either Toolbar or Navigation.

Remaining tasks

User interface changes

API changes

Data model changes