Fix: support validation for map values with struct types

[JunaidIslam2105]

Fixes

Fixed support for validating struct values inside map fields. Previously, if no tag followed endkeys, the struct values were skipped. This PR ensures such struct values are still validated according to their own tags.

Enhancements to validation logic:

• Updated validator.go to handle map values that are structs or pointers to structs by diving into their fields for validation.
• Added test cases covering struct validation in maps, including basic rules, pointer structs, nested structs, and edge cases like nil pointers.

Check #1430 for more details.

Make sure that you've checked the boxes below before you submit PR:

• Tests exist or have been written that cover this particular change.

@go-playground/validator-maintainers

[coveralls]

coverage: 73.674% (+0.01%) from 73.661%
when pulling fe71d89 on JunaidIslam2105:map-struct-validation-bug
into 5b9542b on go-playground:master.

[JunaidIslam2105]

Hi @nodivbyzero, I’m new here. I’d really appreciate it if you could kindly take a look whenever you get a chance.

[nodivbyzero]

Hi @nodivbyzero, I’m new here. I’d really appreciate it if you could kindly take a look whenever you get a chance.

Thanks for making these changes!
Everything looks good to me - just a small suggestion regarding the asserts.

[JunaidIslam2105]

Hey @nodivbyzero, thanks for the kind guidance. I have refactored the tests to use Equal/NotEqual to keep things consistent with the rest of the codebase and added comments as well. Let me know if I need to make any other changes.