fix(mysql): Update default mysql collation to utf8mb4_bin

[jjoyce0510]

Previously, the collation we were using for permitting unicode and emoji style characters was case insensitive. This was causing conflicts among URNs that had the same characters but different casing. This PR updates the default to use a case sensitive collation.

Existing deployments can be updated to use the new collation by executing the following command against your SQL store (verified against MySQL):

ALTER TABLE metadata_aspect_v2 CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_bin;

Verified this works on demo.datahubproject.io, which previously was erroring out on URNs that were same exception for casing.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)

[github-actions]

Unit Test Results

  39 files  ±0    39 suites  ±0   19m 33s ⏱️ + 1m 37s
314 tests ±0  314 ✔️ ±0    0 💤 ±0  0 ❌ ±0 
963 runs  ±0  941 ✔️ ±0  22 💤 ±0  0 ❌ ±0 

Results for commit 3d5ba79. ± Comparison against base commit 561c04b.

[shirshanka]

LGTM!