refactor: remove putIfNotNull and use put API and add PR template

[1abhishekpandey]

Description

• Removed putIfNotNull and instead used put API in the AppInfoPlugin.
• Added Pull Request template. (It's somehow, got removed.)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactor/optimization

Implementation Details

• Use put API for the AppInfoPlugin properties: namespace, version and build, as they are not null.

Checklist

• I have added tests that prove my fix is effective or that my feature works.
• I have added the necessary documentation (if appropriate).
• I have ensured that my code follows the project's code style.
• I have checked for potential performance impacts and optimized if necessary.
• I have checked the code for security issues.
• I have updated the changelog (if required).

How to test?

Make events and note down the context.app if all the four variables are present or not.

{
    "anonymousId": "bab99fd6-3327-4409-9515-cfefebd350a4",
    "channel": "mobile",
    "context": {
        "app": {
            "build": "100",
            "name": "Rudder-Android-Libs",
            "namespace": "com.rudderstack.android.sampleapp",
            "version": "0.1.0"
        },
        "device": {
            "adTrackingEnabled": true,
            "id": "11c89c643bfb7b71",
            "manufacturer": "Google",
            "model": "sdk_gphone64_arm64",
            "name": "emu64a",
            "type": "Android"
        },
        "key": "value",
        "library": {
            "name": "com.rudderstack.sdk.kotlin",
            "version": "1.0.0-alpha.1"
        },
        "locale": "en-US",
        "network": {
            "bluetooth": false,
            "carrier": "T-Mobile",
            "cellular": true,
            "wifi": false
        },
        "os": {
            "name": "Android",
            "version": "14"
        },
        "screen": {
            "density": 560,
            "height": 2808,
            "width": 1440
        },
        "sessionId": 1734509653,
        "timezone": "Asia/Kolkata",
        "traits": {
            "anonymousId": "bab99fd6-3327-4409-9515-cfefebd350a4"
        }
    },
    "event": "Application Opened",
    "integrations": {
        "All": true,
        "CleverTap": true
    },
    "messageId": "a0fb3653-42b5-4af1-9512-643708552dbd",
    "originalTimestamp": "2024-12-19T08:02:33.247Z",
    "properties": {
        "from_background": false,
        "version": "0.1.0"
    },
    "receivedAt": "2024-12-19T08:02:44.743Z",
    "request_ip": "103.51.119.102",
    "rudderId": "f80c9d59-d0fc-4dbd-9b63-14bf5600d75a",
    "sentAt": "2024-12-19T08:02:43.003Z",
    "type": "track"
}

Breaking Changes

Maintainers Checklist

• The code has been reviewed.
• CI tests have passed.
• All necessary documentation has been updated.

Screenshots (if applicable)

Additional Context