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GH-37465: [Go] Add Value method to BooleanBuilder (#37459)



### Rationale for this change

Similar to the changes we've made in #35744 we need this for the BooleanBuilder too.

### What changes are included in this PR?

Adding the method itself and adjusting a test to test both the Value method on the builder and the final array.

### Are these changes tested?

Yes

### Are there any user-facing changes?

Just an enhancement to get on-par with other builders.

* Closes: #37465

Authored-by: Matthias Loibl <mail@matthiasloibl.com>
Signed-off-by: Matt Topol <zotthewizard@gmail.com>