Add webp support

[tksheppard]

Related to Issue

Fixes #250

Description

• Added imagemin-webp to optimize existing webp files
• Added gulp-webp to convert other image types to webp
• Updated imagemin to most recent version
• Added variables calling plugins
• Split Images task into 2 tasks
  • Optimize: Goes through and optimizes all images in src images folder, outputting into dist images
  • Convert: Converts all images to webp and places into dist images
• Changes task images to be a series that runs Optimize and Convert tasks. This series outputs optimized images and a webp version or each image into the dist image folder. src images are untouched.

How Has This Been Tested?

I ran a full build process with several types of images (including webp) in the src folder and checked the output images. I cleared out the dist folder several times to make sure I was testing from a clean output.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[david-poindexter]

Woo hoo - thanks @tksheppard 🎉