Add .clang-format

[asmaloney]

Here is a first attempt to clang-format as close to the existing format as possible (#332).

I formatted the whisper and ggml files to show what it does. If there's anything here you absolutely won't accept, please let me know and I'll see if I can fix it or find a workaround.

Notes:

• The header files were not consistent with indenting the "extern" block. I chose the no-indent style, but it's easy to change.
• Some table-like declarations in whisper.cpp are almost impossible to format the way they were, so the formatter was turned off for them using // clang-format off.
• The unusual formatting in the case statement in whisper_full_default_params got mangled. We can either change the way this is commented or turn off formatting for that section as well.

As noted, some formatting can be turned off using // clang-format off but in general I think this should be discouraged.

[ggerganov]

On second thought, I think .clang-format is not a good option. In this project, I use a unique code formatting where sequential lines are vertically aligned and I really like it this way. I don't think there is a way for .clang-format to achieve this.

[asmaloney]

If you mean these:

struct ggml_tensor * ggml_scale(
        struct ggml_context * ctx,
        struct ggml_tensor  * a,
        struct ggml_tensor  * b);

struct ggml_tensor * ggml_scale(struct ggml_context * ctx, struct ggml_tensor * a, struct ggml_tensor * b);

Indeed at the time I could not figure out how to force that properly. 🤔

It's just that without auto-formatting it makes it more difficult for others to contribute & you will probably have to waste time paying attention to & fixing the formatting for any PRs (especially since the code already isn't self-consistent).