Feat: Implement Custom i18n Package for Embedded Chat (NEW)

[dhairyashiil]

Brief Title

Feat: Implement Custom i18n Package for Embedded Chat (NEW)

Acceptance Criteria fulfillment

• [X] Custom i18n Package Implementation
• [X] Language Files Creation (e.g., en.i18n.json, es.i18n.json, fr.i18n.json, etc.)
• [X] Dynamic Language Switching
• [X] Fallback to Default Language
• [X] Full Translation Coverage

Fixes #945

Video/Screenshots

https://github.com/user-attachments/assets/55a311ec-f26c-4ff6-9c10-8d0b9286a63a

PR Test Details

Note: The PR will be ready for live testing at https://rocketchat.github.io/EmbeddedChat/pulls/pr-951 after approval. Contributors are requested to replace <pr_number> with the actual PR number.

[dhairyashiil]

Hello @Spiral-Memory Habibi come to Dubai

https://github.com/user-attachments/assets/1bcb6109-122e-4f2b-8472-c263bafef385