If a boolean type is compared to a string literal with
the value "true", it should just output that boolean
type unchanged (or prefixed with "not" if ifneq).
Fixes: 206637085
Test: go test
Change-Id: I0c116bb68b96d21ba3783c01fc4ca524aaa04143
Previously, only comparisons between strings/variable references
and other strings/variable references or certain function calls
were allowed. After this cl, any two starlark expressions can
be compared. If they have different types, they will be converted
to strings first.
Fixes: 205995738
Bug: 201700692
Test: go test
Change-Id: Ib463de7b24d3abcd032dbdcba7c3f1351c314d01
