[META] Improve sspport for semantic versioning for extensions (modules, themes, etc) in Drupal core

Problem/Motivation

Follow-up from #3009338: [META] Support semantic versioning for extensions (modules, themes, etc) in Drupal core, and allow modules to be compatible with Drupal 8 and 9 at the same time → with all the unfinished "could-have" or "to-triage" issues. Core supports SemVer releases of contrib now, and has for a while, but it's still a little rough around the edges.

Steps to reproduce

Proposed resolution

Remaining tasks

Could-have

• (not needed but helpful) 📌 Convert update_calculate_project_update_status() into a class Needs work
• (recommended for 9.1.x, and potentially 8.9.x/9.0.x if completed in time) #3005229: Provide optional support for using composer.json for dependency metadata →

Needs triage

1. 📌 A pre-release update will be recommended for semantic version updates if the patch number is equal to the patch number from the previous release Needs work
2. #3105463: Create tests for recommended bugfix releases →
3. #3076183: [Meta] Determine how available updates for modules should be handled if they are not compatible with the current version of Drupal core →
4. 📌 Remove Drupal::CORE_COMPATIBILITY because it is not accurate when modules can be compatible with multiple core branches Active
5. 📌 Decide what to do with Drupal::CORE_MINIMUM_SCHEMA_VERSION and surrounding logic Active

Could-have

• (not needed but helpful) 📌 Convert update_calculate_project_update_status() into a class Needs work
• (recommended for 9.1.x, and potentially 8.9.x/9.0.x if completed in time) #3005229: Provide optional support for using composer.json for dependency metadata →

Needs triage

1. 📌 A pre-release update will be recommended for semantic version updates if the patch number is equal to the patch number from the previous release Needs work
2. #3105463: Create tests for recommended bugfix releases →
3. #3076183: [Meta] Determine how available updates for modules should be handled if they are not compatible with the current version of Drupal core →
4. 📌 Remove Drupal::CORE_COMPATIBILITY because it is not accurate when modules can be compatible with multiple core branches Active
5. #3113992: The 'Update' page has no idea that some updates are incompatible →
6. 📌 Determine specific version of SemVer supported by Drupal due to differences in pre-release notation. Active

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet