Refactor deserialization of SearchEntry

[keaz]

This pull request includes several changes to the simple-ldap project, primarily focusing on updating dependencies and refactoring the LdapClient implementation to simplify JSON handling and mapping of search results to structs.

Dependency Updates:

• Updated the version in Cargo.toml from 2.1.0 to 2.1.1.
• Added serde-value = "0.7.0" to the dependencies in Cargo.toml.

Refactoring JSON Handling:

• Removed the create_json_signle_value, create_json_multi_value, and map_to_struct methods from LdapClient and replaced them with to_signle_value and to_multi_value functions for converting search results directly to structs using serde_value. [1] [2] [3]
• Updated the to_record and to_multi_valued_record_ methods in the Record struct to use the new to_signle_value and to_multi_value functions.

Test Adjustments:

• Modified the test cases to use the new to_signle_value and to_multi_value functions instead of the removed JSON creation and mapping methods. [1] [2] [3]