Adding benchmark tests over some popular queries

[abhinavdangeti]

Here're results on my computer:
```
[12:52:04] AD: ~/Documents/go/src/github.com/blevesearch/bleve $ go test -run=BenchmarkQuery -bench=BenchmarkQuery -v
goos: darwin
goarch: amd64
pkg: github.com/blevesearch/bleve/v2
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkQueryTerm
BenchmarkQueryTerm-12                     181676              6309 ns/op            4130 B/op         59 allocs/op
BenchmarkQueryTermRange
BenchmarkQueryTermRange-12                 72004             16440 ns/op            7286 B/op         94 allocs/op
BenchmarkQueryWildcard
BenchmarkQueryWildcard-12                   4686            251194 ns/op          124294 B/op        291 allocs/op
BenchmarkQueryNumericRange
BenchmarkQueryNumericRange-12              59023             20151 ns/op           12760 B/op        155 allocs/op
BenchmarkQueryDateRange
BenchmarkQueryDateRange-12                 34382             33578 ns/op           18647 B/op        256 allocs/op
BenchmarkQueryGeoDistance
BenchmarkQueryGeoDistance-12               24669             41800 ns/op           26878 B/op        279 allocs/op
BenchmarkQueryGeoBoundingBox
BenchmarkQueryGeoBoundingBox-12            14122             84857 ns/op           47915 B/op        352 allocs/op
PASS
ok      github.com/blevesearch/bleve/v2 507.927s

```