Refactor bindgen snapshot unit tests to use insta

[agostbiro]

As @frol suggested in #1036 (comment) we should refactor bindgen snapshot unit tests to use the insta crate.

Unit tests that could benefit from this:

near-sdk-rs/near-sdk-macros/src/core_impl/code_generator/item_impl_info.rs

Line 30 in c39fba3

mod tests {

near-sdk-rs/near-sdk-macros/src/core_impl/code_generator/item_trait_info.rs

Line 30 in c39fba3

mod tests {

near-sdk-rs/near-sdk-macros/src/core_impl/code_generator/ext.rs

Line 146 in c39fba3

mod tests {

near-sdk-rs/near-sdk-macros/src/core_impl/abi/abi_generator.rs

Line 295 in 6887b41

mod tests {

[jaswinder6991]

Hi @agostbiro, are you working on this issue? If not, I would like to try it out.

[iho]

@agostbiro @jaswinder6991 @frol Do we have any progress? Can I take this task?

[frol]

@iho Please, go ahead! Take inspiration from borsh-rs setup.