Update azure-resources module to follow style guide

[Copilot]

This PR updates the azure-resources module to comply with all recommendations in the style guide, making minimal surgical changes as requested.

Changes Made

Build Configuration

• Fixed incorrect description and module name in build.gradle.kts that referenced "GCP" instead of "Azure"

Class Declarations

Added final keyword to public non-internal classes per style guide requirement:

• AzureResourceDetector
• AzureAppServiceResourceProvider
• AzureMetadataService
• AzureFunctionsResourceProvider
• AzureVmResourceProvider
• AzureAksResourceProvider
• AzureContainersResourceProvider

Static Imports

Added recommended static imports from the style guide:

• java.util.Objects.requireNonNull in AzureMetadataService and AzureAppServiceResourceProvider
• io.opentelemetry.sdk.testing.assertj.OpenTelemetryAssertions.assertThat in test files

Class Organization

Reorganized classes to follow the recommended order (static fields, instance fields, constructors, methods, nested classes):

• Moved Entry nested class to end of AzureVmResourceProvider
• Moved private constructor to end of AzureMetadataService (static utility class pattern)
• Grouped static fields together in proper order

Verification

• All 22 tests continue to pass
• Code formatting remains compliant with spotlessApply
• Changes are minimal and surgical (12 files modified)

Fixes #371.

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