Convert charset to utf8mb4 to resolve invalid character issues

[dadarya0]

Q	A
Bug fix? (use the a.b branch)	No
New feature/enhancement? (use the a.x branch)	Yes
Deprecations?	[ ]
BC breaks? (use the c.x branch)	[ ]
Automated tests included?	No
Related user documentation PR URL	mautic/mautic-documentation#...
Related developer documentation PR URL	mautic/developer-documentation#...
Issue(s) addressed	Fixes #...

Description:

Older instances that were created before the MySQL8 upgrades are using an outdated format. By migrating all tables issues like character encoding will be resolved.

Steps to test this PR:

1. Open this PR on Gitpod or pull down for testing locally (see docs on testing PRs here)
2. Make sure your table does not have utf8mb4 charset
3. Insert some Japanese character in text field or description field.
4. it should be saved and rendered properly
5. search filter should work fine.

[escopecz]

I see no issue with the code. I've run the migration but I don't have a database that would have other than utf8mb4_unicode_ci encoding so it did nothing.