🐛 Bug Report: Don't Allow Empty Title & Message Body for Messaging

### 👟 Reproduction steps

Currently it seems possible to use only white space to compose an empty Subject/Title & Message Body.
This causes one to send a completely empty message which may not be right (atleast for Push Notifs).

### 👍 Expected behavior

Don't allow sending empty messages.

### 👎 Actual Behavior

We can send empty messages.

### 🎲 Appwrite version

Version 1.5.x

### 💻 Operating system

MacOS

### 🧱 Your Environment

_No response_

### 👀 Have you spent some time to check if this issue has been raised before?

- [X] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [X] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)