fix(#666): Add builder for non-exhaustive structs

[hadizamani021]

issue (#666)

[sunng87]

@hadizamani021 Thank you! You can use derive_builder crate to generate builders for this case.

[coveralls]

coverage: 82.062% (+0.04%) from 82.024%
when pulling 111cb9f on hadizamani021:feat/add-builder-for-non-exhaustive-structs
into 190bc3b on sunng87:master.

[sunng87]

LGTM. Is there any other struct to add builder?

[hadizamani021]

@sunng87 Thank you sunng, I added for all non_exhaustive structs.

[sunng87]

@hadizamani021 Thank you!