[DRAFT] Tried to add direct calls example, but init fails

[iliakan]

The natural thing for wasm is to call functions from JS directly or using cwrap, but I failed to do so.

In short, this fails:

let repoPointer = Module._malloc(8);

// int git_repository_init(git_repository **out, const char *path, unsigned int is_bare);
let git_repository_init = Module.cwrap('git_repository_init', 'number', ['number','string','number']); 

let r1 = git_repository_init(repoPointer, "/working", 0); // -1 (failed)

I tracked the problem inside libgit2.

The root of the issue is here: https://github.com/libgit2/libgit2/blob/main/src/util/str.c#L86

This grealloc call (which appears to use the stdalloc realloc) doesn't work, new_ptr becomes 0.
May it be connected with some memory issues? Or did I screw up somewhere? ;)

This PR contains a few changes I made to use git_repository_init.
Not intended for merging. Once I figure out the problem, I'll be able to submit a better variant.