Wildcard tree search enhancement and tests

[ramon-bernardo]

Pull Request Prelude

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

Changes Proposed:

• Tests: Added comprehensive unit tests to verify the functionality of the WildcardTree.

• Code modernization: Utilized auto in appropriate places to enhance code readability and maintainability. For further insights, please refer to Herb Sutter's explanation.

• Function renaming: Updated function names to follow snake_case for consistency with modern C++.

• Search behavior refinement: Modified the search function to return a more descriptive result using a pair consisting of a custom SearchResult enum and the matched string. This change eliminates the need for the previous ReturnValue.

• Namespace: Removed the instantiation of a root, updating all usages to directly utilize the tfs::game::wildcardtree namespace, which enhances clarity and reduces potential errors.

Memory management improvements

• Transitioned from raw pointers to std::shared_ptr for improved memory safety, significantly reducing the risk of memory leaks and ensuring proper resource management throughout the WildcardTree implementation.

Usage

// Example of adding and searching for strings in the WildcardTree
tfs::game::wildcardtree::add("hello");
tfs::game::wildcardtree::add("world");

// Search for an exact match for "hello".
auto search_result = tfs::game::wildcardtree::search("hello");
if (search_result.first == WildcardTreeSearchResult::Found) {
    // Found exact match
}

// Search for a non-existing string.
search_result = tfs::game::wildcardtree::search("nonexistent");
if (search_result.first == WildcardTreeSearchResult::NotFound) {
    // The string was not found
}

// Remove the string "world" from the WildcardTree.
tfs::game::wildcardtree::remove("world");

[ramon-bernardo]

Ready for review and merge! @ranisalt ;)