Wildcard tree search enhancement and tests

[ramon-bernardo]

Pull Request Prelude

• I have followed proper The Forgotten Server code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

• Add tests for the wildcard tree.
• Improve codebase using auto where possible and renaming the search function for clarity.
• Return a pair with an enum directly associated with Wildcard, instead of ReturnValue.
• Rename the functions to snake_case.
• Use std::shared_ptr instead raw pointers.