Add unit tests for the `kmemory` module

[iWas-Coder]

Describe the feature

Add test coverage for the kmemory module.

Why should it be implemented? (optional)

The kmemory module is a core component of the engine, thus various parts depend on it; if it does not work as expected, it could create problems in some critical places.

Do you think there is any alternative? (optional)

N/A

Additional context (optional)

• To start working on this, take a look at #31; it is the same, but with the kmemory module instead of the kstring.
• Be sure to run make check and both new and prexistant tests succeed without unexpected errors.

Extra questions (optional)

• I have used the search function to check if an issue already exists
• I'd like to work on this issue