Add script for regenerating bindings

[ionut-arm]

This builds on #82 which did the same thing for the 0.2.x version of the crates.

[hug-dev]

Pretty cool!! Will make so easy to add new bindings

[wiktor-k]

Yep, looks good and nice! 👍 (I do miss the LF at the end of regenerate_bindings.sh but it's a minor thing).

[ionut-arm]

I do miss the LF at the end of regenerate_bindings.sh but it's a minor thing

Fixed!

Will make so easy to add new bindings

I need to have a look at adding the same for the other FFI crates.

[wiktor-k]

Btw I ran the script through shellcheck and got the following:

In /tmp/x.sh line 15:
        rustup target install $target
                              ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
        rustup target install "$target"


In /tmp/x.sh line 19:
    cargo build --target $target --features generate-bindings
                         ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
    cargo build --target "$target" --features generate-bindings


In /tmp/x.sh line 20:
    find ../target/$target/ -name pkcs11_bindings.rs | xargs -I '{}' cp '{}' src/bindings/$target.rs
    ^-- SC2038 (warning): Use -print0/-0 or -exec + to allow for non-alphanumeric filenames.
                   ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                                          ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
    find ../target/"$target"/ -name pkcs11_bindings.rs | xargs -I '{}' cp '{}' src/bindings/"$target".rs


In /tmp/x.sh line 23:
        rustup target remove $target
                             ^-----^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 
        rustup target remove "$target"

I'm not a shell expert by any means so you'd have to decide if these lints are something to listen to but I wanted to provide yet another angle :)

[ionut-arm]

Ok, fixed those problems flagged by shellcheck.