feat: add drift extension

[YOU54F]

Add a drift extension to install drift to ~/.drift

It is installed, and is it not on the path, but the pact cli is (for example installed to ~/.pact/bin)

then using pact drift will direct the user to the installed path

pact extension install drift
pact drift auth status 
# export pactflow env vars
pact drift auth status
pact drift verify <options>

can be tested locally with

cargo run extension install drift
cargo run drift auth status 
# export pactflow env vars
cargo run drift auth status
cargo run drift verify <options>

[YOU54F]

Just as a thought, we package up the binary and ship in a docker container, do you think we should pre-install drift and pactflow-ai

https://github.com/pact-foundation/pact-cli/blob/main/docker/Dockerfile.alpine

We don't currently. Thoughts?