[Feature] Support custom time zones for microbatch incremental models

### Is this your first time submitting a feature request?

- [x] I have read the [expectations for open source contributors](https://docs.getdbt.com/docs/contributing/oss-expectations)
- [x] I have searched the existing issues, and I could not find an existing issue for this feature
- [x] I am requesting a straightforward extension of existing dbt functionality, rather than a Big Idea better suited to a discussion

### Describe the feature

Microbatch incremental models are currently supporting UTC time zone as mentioned in the documentation.

https://docs.getdbt.com/docs/build/incremental-microbatch#timezones.

While we believe that defining these values in UTC makes everyone's lives easier, adding support for custom time zones would still provide additional flexibility for different use cases.

### Describe alternatives you've considered

_No response_

### Who will this benefit?

_No response_

### Are you interested in contributing this feature?

_No response_

### Anything else?

_No response_