Allow psycopg2-binary as an alternative to psycopg2

[DavidS-cloud]

Is your feature request related to a problem?

We're using psycopg2-binary to avoid the complications of compiling psycopg2 on deployment. When using the Psycopg2Instrumentor, it fails with "DependencyConflict: requested: "psycopg2 >= 2.7.3.1" but found: "None"". Replacing our psycopg2-binary requirement with regular psycopg2 works just fine, but is very inconvenient for our deployment.

Describe the solution you'd like
Psycopg2Instrumentor can detect and work with both packages.

Describe alternatives you've considered
If it is not possible to have alternate dependencies, another option would be to have a Psycopg2BinaryInstrumentor that just proxies everything to the regular Psycopg2Instrumentor.

[owais]

Dup open-telemetry/opentelemetry-python-contrib#541

[owais]

Let's discuss this over at open-telemetry/opentelemetry-python-contrib#541