Add IonQ as a provider

[splch]

$ cargo clean && cargo fmt
$ export QRMI_IONQ_CLOUD_API_KEY="..."
$ RUST_LOG=info,qrmi=debug,ionq_cloud_api=debug \
  cargo run --manifest-path examples/qrmi/rust/ionq_cloud/Cargo.toml -- \
    --backend simulator \
    --shots 100 \
    --format qasm2

[ohtanim]

@splch Hello, is this PR in a state where it can be merged? If there are any blockers preventing us from moving forward, could you please let me know? Our community is here to support you. Thanks,

[splch]

@splch Hello, is this PR in a state where it can be merged? If there are any blockers preventing us from moving forward, could you please let me know? Our community is here to support you. Thanks,

Thank you! We're getting some things sorted on our end and will probably reopen another PR from another branch. We don't want to merge this but I'll close it once we have another integration branch ready :)

[ohtanim]

@splch Thanks for your response. Understood your plan.