Small linkedlist lib in C

TODOs

nicer Makefile
libcheck unit testing
check memleaks, etc. with valgrind
code coverage report generation with gcov
doxygen documentation
upload on github with proper commit messages
use -g gcc debugging option for use with gdb
config file for code-formatting
revisit codes several times, each time you will get something which can be done in a better way (performance, readability, or style)
- while revisiting the code, we can write documentation, and log lines
I don't like OBJS variable to be at one place, can be spread across multiple Makefiles
I don't like the #include "module/inc/module.h" style now, "inc" word is redundant
struct tags should not start with _, infact any identifier shouldn't start with leading _
list can have a struct ListInstance which gives the user functions by which they can insert/delete/update/find/etc in the list
log level lines instead of printf()s for debugging
I have changed my style from char *var to char* var, also changed curly braces to start on the same line (unless it is a function defintion)
fix github CI unit test
cache github CI workflow/environment so that it doesn't install valgrind etc. on every push
Separate debug bin build (compiled with -g) process and release bin build process

Document somehow that these are dependencies and need to be installed (or make a script that checks for and installs these dependencies)