#21 Refactor classes and add autoconfiguration

[IlyaLisov]

PR-Codex overview

The focus of this PR is to refactor mail service configuration and template handling.

Detailed summary

• Refactored mail service configuration classes
• Updated mail service interfaces and implementations
• Introduced MailTemplate class for email templates
• Modified MailParameters to use String instead of generic type
• Added MailServiceProperties to manage mail service properties
• Updated MailAutoConfiguration to handle mail service bean creation

The following files were skipped due to too many changes: src/main/java/io/github/ilyalisov/mail/service/MailServiceImpl.java

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}