♻️ Stabilization of `EmailAddress` type

[LVMVRQUXL]

📝 Description

We want to stabilize the EmailAddress type and its serializer, provided by the EmailAddress.Companion.stringSerializer() function.

✅ Checklist

See the Issue implementation section in the contributing guidelines before addressing the following checklist.

• ♻️ Stabilize the EmailAddress type.
• ♻️ Stabilize the EmailAddress.Companion.stringSerializer() function.
• 📝 Update the unreleased changelog for this issue.