Fix model of Boolean vars with eager bit-blaster (#2998)

Fix model of Boolean vars with eager bit-blaster (#2998)

When bit-blasting eagerly, we were not assigning values to the Boolean
variables in the `TheoryModel`. With eager bit-blasting, the BV SAT
solver gets all (converted) terms, including the Boolean ones, so
`EagerBitblaster::collectModelInfo()` is responsible for assigning
values to Boolean variables. However, it has only been assigning values
to bit-vector variables, which lead to wrong models. This commit fixes
the issue by asking the `CnfStream` for the Boolean variables, querying
the SAT solver for their value, and assigning them in the `TheoryModel`.