[RUST][FRONTEND] Add rust frontend v0.1

[ehsanmok]

Overview

I'm delighted to submit this PR which adds Rust runtime frontend support as part of RFC 1601.

You can see the dev here. Here's a summary

1. Add tvm_frontend bindings and idiomatic Rust API.
2. Create a common crate refactoring TVMArgValue and TVMRetValue and unifying FFI across runtime and frontend.
3. Various cleaning up and adding more documentations.

@nhynes @tqchen @jroesch

resolves #2306

[nhynes]

nice work so far! a few more comments for your perusal :)

I'm looking forward to having this merged!

[ehsanmok]

@nhynes @tqchen how come CI tvm-sys build is successful (tvm_runtime is found in ld path) as first dependency though tvm_frontend cannot find tvm_runtime?

[nhynes]

tvm_frontend cannot find tvm_runtime

In what context is this bug occurring? The most likely cause is that LD_LIBRARY_PATH simply becomes unset.

[ehsanmok]

@nhynes Please checkout task_rust.sh.

[nhynes]

What happens if you also export LD_LIBRARY_PATH a la https://github.com/dmlc/tvm/blob/master/tests/scripts/task_java_unittest.sh#L3

[ehsanmok]

@nhynes Already exported in tests/scripts/task_rust.sh and I didn't change that.

[jroesch]

I will take a pass over this later today.

[ehsanmok]

@nhynes pinging for the updated PR!

[nhynes]

re-reviewing now!

[nhynes]

nice! this is the last round of changes :)

[nhynes]

I pulled the branch and made some changes w.r.t. returning references instead of sprinkling in to_owneds

[nhynes]

We're going to need to work on error messages

thread 'main' panicked at '', tvm_rust/rust/frontend/src/function.rs:262:13
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

isn't a very helpful output of checked_call! :(

[ZihengJiang]

@nhynes The jenkins image has been updated. Please submit an empty commit to retrigger the CI

[tqchen]

Sorry, I have to revert the image due to a short outrage to recover ANTLR, will send in update