Adding powerplatform_environment_settings resource and datasource

[mawasile]

This pull request introduces changes to the Power Platform provider, specifically adding support for environment settings. The changes include the introduction of a new data source and resource for environment settings, updates to the documentation, and the addition of new test cases.

Data source and resource addition:

• internal/powerplatform/provider.go: Added the new EnvironmentSettingsResource and EnvironmentSettingsDataSource to the provider's resources and data sources respectively. [1] [2]

Documentation updates:

• docs/data-sources/environment_settings.md: Added documentation for the new powerplatform_environment_settings data source.
• docs/data-sources/tenant_application_packages.md: Added documentation for the new powerplatform_tenant_application_packages data source.
• docs/resources/environment_settings.md: Added documentation for the new powerplatform_environment_settings resource.
• docs/resources/user.md: Updated the formatting of the links in the documentation for the powerplatform_user resource.

Test case addition:

• internal/powerplatform/datasource_environment_settings_test.go: Added new test cases for the powerplatform_environment_settings data source.

Example updates:

• examples/data-sources/powerplatform_environment_settings/datasource.tf: Added an example for the usage of the powerplatform_environment_settings data source.
• examples/data-sources/powerplatform_environment_settings/outputs.tf: Added an output for the example of the powerplatform_environment_settings data source.
• examples/resources/powerplatform_environment_settings/outputs.tf: Added an output for the example of the powerplatform_environment_settings resource.
• examples/resources/powerplatform_environment_settings/resource.tf: Added an example for the usage of the powerplatform_environment_settings resource.