Support for PHP 7.4 and PHP 8.0

[frost-byte]

There is a lot to cover in this PR.

Here is a list of just some of the changes:

• Add support for PHP7.4 and PHP 8.0
• Use bionic instead of xenial for all Docker Images
  • Provides newer version of ssl1.1 out of the box
• Keep support for 7.3, but remove previous versions < 7.4
• Miscellaneous Changes
  • Update tests to use latest version of phpunit (v.9.5.4)
  • Update extensions to newer/more recent builds
  • Added a function for using latest commit from git for building extensions
    • imagick
    • phalcon
    • pq
    • raphf
    • stackdriver_debugger
    • v8js
• Libraries
  • Add librabbitmq to support newer version of the amqp extension
  • Cassandra uses libuv provided by Datastax
  • Removed libvips, can now use version bundled with bionic (libvips42)
• Extensions that are now built into PHP natively and no longer bundled as separate extensions
  • apcu
  • jsond/jsonc (7.4, 8.0 are built in)
  • sodium
• Extensions that are obsolete
  • apcu_bc (7.4, 8.0 are built in)
• Extensions that require updates upstream for php8
  • hprose
  • lua
  • opencensus (official compatible release should be coming soon)
  • phalcon
  • stackdriver_debugger (I'm testing/updating a fork to support php8)
  • tcpwrap
• Extensions not building
  • v8js - could not find libv8_libplatform library

There are a few things that still need to be reviewed:

• Re-enable license checks in container structure testing (testapps containers)
• Run End-to-End tests
• The previous nginx configuration/version used was no longer recognizing the set_by_lua directive, I have switched to using the ppa from Ondrej for nginx-mainline v1.19; if I can determine enable the lua module for the package in bionic, then that can be used in its place

I have included a NOTES.md file containing some of the steps required to build packages, create distributions and build images. Some of this information is spread about in the previous release, but some was not clear.

Additional customizations have also been added, so you can specify your own GCS buckets and use your GCP Project ID to host the containers and package artifacts for the distributions you create for each PHP version supported.

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[google-cla[bot]]

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[frost-byte]

I'm going to fix issues with the repo caused by removing the .cache file from the previous commits.

[google-cla[bot]]

All (the pull request submitter and all commit authors) CLAs are signed, but one or more commits were authored or co-authored by someone other than the pull request submitter.

We need to confirm that all authors are ok with their commits being contributed to this project. Please have them confirm that by leaving a comment that contains only @googlebot I consent. in this pull request.

Note to project maintainer: There may be cases where the author cannot leave a comment, or the comment is not properly detected as consent. In those cases, you can manually confirm consent of the commit author(s), and set the cla label to yes (if enabled on your project).

ℹ️ Googlers: Go here for more info.

[frost-byte]

Going to close this and resubmit it...