enhancement: improve the equality check

[hgiasac]

This pull request refactors the implementation of the Equal methods for environment variable wrapper types (EnvString, EnvInt, EnvBool, EnvFloat, and EnvAny) to improve clarity and maintainability. Additionally, it consolidates and relocates their unit tests into the main test files, removing redundant test files.

Refactoring of equality logic:

• Simplified the Equal methods for EnvString, EnvInt, EnvBool, EnvFloat, and EnvAny to return early if values differ, making the logic clearer and more efficient. The methods now check for value equality first and only compare variable names if values match. (environment.go [1] [2] [3] [4]; any.go [5]

Test consolidation and cleanup:

• Moved all Equal method tests for the environment types from their dedicated test files (environment_equal_test.go, any_equal_test.go) into the main test files (environment_test.go, any_test.go), and deleted the now-redundant test files. This improves test organization and reduces duplication. (environment_equal_test.go [1] any_equal_test.go [2] environment_test.go [3] any_test.go [4]

No functional changes were made to the behavior of the Equal methods; this is a code quality and maintainability improvement.