main.c: remake cli tool, helper.c: add strcmp, use builtins in some paths

Co-authored-by: tema5002 <tema5002@tuta.io>
Reviewed-on: NeoFlock/noom#4
Co-committed-by: tema5002 <tema5002@tuta.io>

src/helper.h

@@ -3,6 +3,7 @@
 int noom_startswith(const char* str, const char* compare);
 int noom_streql(const char* stra, noom_uint_t lena, const char* strb, noom_uint_t lenb); // rename to something better?
 noom_uint_t noom_strlen(const char *s);
+int noom_strcmp(const char *a, const char* b);
 void noom_safe_strcpy(char* buffer, noom_uint_t* pos, noom_uint_t buffer_size, const char* src);
 
 void* noom_alloc(noom_uint_t size);