Normalize Android lesson activity naming and add lesson contributor template

[MihaiCristianCondrea]

Motivation

• Ensure lesson Activity class names and filenames follow a strict, predictable convention so tooling and registration points work reliably.
• Provide a short contributor guide so new lessons are added with the required package layout, raw files, and manifest/preferences registration.

Description

• Renamed lesson activities to follow the <Lesson>Activity convention: GirdViewActivity → GridViewActivity, AndroidHistory → AndroidHistoryActivity, and AndroidSDK → AndroidSdkActivity, including renaming Java files under ui/screens/android/lessons/.
• Updated all registration references to match the new class names in app/src/main/AndroidManifest.xml and in the lesson listing app/src/main/res/xml/preferences_android_studio.xml intent android:targetClass values.
• Fixed the view binding import/usage in the history lesson to use ActivityAndroidHistoryBinding and updated activity class declarations to match filenames.
• Added a contributor guide section to docs/general/style-guidance.md documenting the required lesson package structure, required raw files (text_<lesson>_java.txt and text_<lesson>_xml.txt), registration points, and naming rules.

Testing

• Ran a static Python sweep to detect class/file-name mismatches and activity naming outliers under app/src/main/java/com/d4rk/androidtutorials/java/ui/screens/android/lessons/, which reported no remaining mismatches after the changes (success).
• Ran ./gradlew test, which failed in this environment because the Android SDK location is not configured (missing ANDROID_HOME / local.properties sdk.dir), so unit/instrumented tests could not be executed here (environment limitation).

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Codex Task