Errors for missing composer or rsync executables on the status reports page should link to a docs page

Problem/Motivation

📌 Remove the ability to configure the path to Composer Active is removing the ability to configure the path to composer. composer has to be either globally available in the $PATH or to be installed as a runtime dependency (*rsync doesnt have that runtime requirements test analogues to composer yet - see ✨ Add a runtime requirements test for rsync analogues to composer Active ).

if composer is not available package_manager is throwing the following error on the status reports page:

For less technical folks and/or people new to drupal, the statement "Make sure it's installed..." might pose a significant obstacle. At least it requires the person unfamiliar with drupal to research on their own how to install the missing executable, and for less technical folks that task might be simply overwhelming.

Steps to reproduce

Proposed resolution

it would be good, instead of stating "Make sure it's installed..." to link to a docs page instead, that is providing clear and directly actionable steps how to install composer and or rsnyc.

the linked docs page could either be a newly created one of one or two specific sections could be added to for example https://www.drupal.org/docs/develop/core-modules-and-themes/core-modules... → as suggested by @benjifisher here.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet