Closes #3725: Hard code higher WebP conversion quality setting until configurable for GD in core.

[joeparsons]

Description

Alternative PR for #3725 that adds custom Drupal core patch that just hard-codes increased WebP conversion quality value in Drupal core's GD image toolkit code.

Related issues

Closes #3725

How to test

Types of changes

Arizona Quickstart (install profile, custom modules, custom theme)

• Patch release changes
  • Bug fix
  • Accessibility, performance, or security improvement
  • Critical institutional link or brand change
  • Adding experimental module
  • Update experimental module
• Minor release changes
  • New feature
  • Breaking or visual change to existing behavior
  • Upgrade experimental module to stable
  • Enable existing module by default or database update
  • Non-critical brand change
  • New internal API or API improvement with backwards compatibility
  • Risky or disruptive cleanup to comply with coding standards
  • High-risk or disruptive change (requires upgrade path, risks regression, etc.)
• Other or unknown
  • Other or unknown

Drupal core

• Patch release changes
  • Security update
  • Patch level release (non-security bug-fix release)
  • Patch removal that's no longer necessary
• Minor release changes
  • Major or minor level update
• Other or unknown
  • Other or unknown

Drupal contrib projects

• Patch release changes
  • Security update
  • Patch or minor level update
  • Add new module
  • Patch removal that's no longer necessary
• Minor release changes
  • Major level update
• Other or unknown
  • Other or unknown

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My change requires release notes.

[tadean]

@joeparsons patch does seem to enable lossless compression if it's available:

webpinfo lynx.jpg.webp 
File: lynx.jpg.webp
RIFF HEADER:
  File size: 1909782
Chunk VP8L at offset     12, length 1909770
  Width: 1920
  Height: 1080
  Alpha: 0
  Animation: 0
  Format: Lossless (2)
No error detected.

[bberndt-uaz]

Comparing the front pages of the Probo site for this PR with the front pages of previous PRs, it looks like the size of the Lynx image goes from 182 kB to 1.9 MB.

[bberndt-uaz]

With the latest version, the size of the Lynx image is 388 kB, which seems good to me.