Change default mysql collation to utf8mb4_general_ci

[rfay]

The Problem/Issue/Bug:

In TYPO3 slack we studied extensively why a few collation variables weren't the utf8mb4_general_ci variables we expected.

How this PR Solves The Problem:

• change collation-server, which also results in the default database creation with the correct collation.
• add init_connect='SET collation_connection = utf8mb4_unicode_ci', which auto-changes the client connection.

Manual Testing Instructions:

• Delete your existing database or create a new project. mkdir testcoll && cd testcol && ddev config --project-type=php && ddev start
• echo "SHOW VARIABLES LIKE 'coll%';" | ddev mysql

You should see all collation variables being utf8mb4_general_ci

$ echo "SHOW VARIABLES LIKE 'coll%';" | ddev mysql
mysql: [Warning] Using a password on the command line interface can be insecure.
Variable_name	Value
collation_connection	utf8mb4_unicode_ci
collation_database	utf8mb4_general_ci
collation_server	utf8mb4_general_ci

You should see

Automated Testing Overview:

Related Issue Link(s):

Release/Deployment notes:

[rfay]

@jeffsheltren would appreciate your review of this one, thanks!

[jeffsheltren]

Looks good to me!

[rfay]

Thanks @jeffsheltren - this will go into v1.15+

[rfay]

Artifacts for anybody to test this are at https://app.circleci.com/pipelines/github/drud/ddev/2038/workflows/d9c246c8-3c04-4f00-97c9-fc6a2440b06d/jobs/24242/artifacts