Fix KtLint issues & other CI related issues

[brionmario]

Purpose

Fixes KtLint formatting violations and unblocks CI. Also adds missing Gradle wrapper files and corrects composite build configuration in the quickstart sample so it resolves dependencies and builds independently.

Approach

• Added .editorconfig with ktlint_function_naming_ignore_when_annotated_with = Composable to suppress false-positive KtLint failures on @Composable functions.
• Added root-level Gradle wrapper (gradlew, gradlew.bat, gradle/wrapper/).
• Fixed samples/quickstart/settings.gradle.kts to include dependencyResolutionManagement with google() and mavenCentral() — composite build dependency repos don't propagate from included builds to the consumer project.
• Added samples/quickstart/gradle.properties with android.useAndroidX=true — the SDK root's gradle.properties is not inherited by the quickstart composite build.
• Declared AGP and Kotlin plugin versions explicitly in samples/quickstart's pluginManagement.plugins block — the com.android.library version in the composite build doesn't propagate to com.android.application in the consumer project.

Related Issues

• Thunder Android SDK thunderid#2122

Related PRs

• N/A

Checklist

• Followed the contribution guidelines.
• Manual test round performed and verified.
• Documentation provided. (Add links if there are any)
• Tests provided. (Add links if there are any)
  • Unit Tests
  • Integration Tests
• Breaking changes. (Fill if applicable)
  • Breaking changes section filled.
  • breaking change label added.

Security checks

• Followed secure coding standards in WSO2 Secure Coding Guidelines
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets.