refactor lmi and trt dockerfiles to install python requirements from …

[siddvenk]

…requirements file

Description

This PR changes our dockerfile to install python dependencies via a requirements file. This is easier to parse than the full set of versions and dependencies in our docker file.

Additionally, it gives us the ability to:

• specify version ranges, or less strict version requirements per dependency
• ensure we install compatible versions of dependencies by relying on the pip dependency resolver

Few more change I want to make before moving out of the draft stage, but this is more or less what it will look like.
I've tested the integ tests locally to verify the newly built containers are functioning as expected.