feat(doc): Doxyfile revamp to Doxygen v1.9.8

This update addresses the Doxygen warnings on deprecated configurations.
The version update itself was performed with doxygen assistance.

On top of it, many improvements to the configuration have been performed
manually (see below).

To improve clarity, the following have been set/altered:

- PROJECT_NAME
- PROJECT_NUMBER
- PROJECT_BRIEF

Furthermore, this commit is part of an effort to document core files'
functions. As such, the following configuration has been altered to
(at least temporarily) prevent warnings and errors from doxygen.

- EXTRACT_LOCAL_CLASSES
- HIDE_UNDOC_MEMBERS
- WARN_IF_UNDOC_ENUM_VAL
- HIDE_UNDOC_MEMBERS
- EXTRACT_LOCAL_CLASSES
- EXCLUDE_PATTERNS

As a clarifying note on EXCLUDE_PATTERNS: files in src/arch and
src/platform, header files and remio.c are brought outside the scope
of Doxygen to avoid errors.

These files either

1. Lack documentation;
2. The documentation is insufficient;
3. The documentation is using custom formatting (e.g. @vm).

In the opinion of the author, `remio.c` requires many QA improvements,
many of which can result in a documentation rewrite.
For this reason, the file has been excluded from doxygen's scope.

The following settings are enabled for strict quality control over
function documentation:

- WARN_IF_INCOMPLETE_DOC
- WARN_NO_PARAMDOC

Finally, the following settings have been enabled to invite the use of
Doxygen in the CI:

- WARN_AS_ERROR
- NUM_PROC_THREADS
- TIMESTAMP

Signed-off-by: Aras Ashraf Gandomi <aras.gandomi@gmail.com>

Author: 0utd4ted