Make typeshare an optional dependency

[iinuwa]

Upstreaming bitwarden#14:

Make the typeshare dependency optional since it's generally not required. Due to some rust limitations I had to duplicate two struct fields.

[Progdrasil]

LGTM, You'll just need to fix the pipeline

[iinuwa]

Looks like we need to duplicate those two fields mentioned in the review because the typeshare field attribute is a macro attribute, but cfg_attr only supports non-macro attributes. (This is different from serde, whose struct attributes is a macro attribute, but the field attributes are non-macro attributes.)

I reverted back to the original code. I'll do a separate PR to fix the Clippy lints.

[Progdrasil]

For the cfg_attr, this will be blocked on 1Password/typeshare#273