feat(tvix/build): init

This adds the tvix-build crate, currently only containing a
`tvix_build::proto` module, exposing the data structures defined in
tvix/build/protos.

Change-Id: I75f5d9196969ed0877b1fe640cacfecba0fb2e03
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10235
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI

tvix/build/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "tvix-build"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+prost = "0.12.1"
+tonic = "0.10.2"
+tvix-castore = { path = "../castore" }
+
+[dependencies.tonic-reflection]
+optional = true
+version = "0.10.2"
+
+[build-dependencies]
+prost-build = "0.12.1"
+tonic-build = "0.10.2"
+
+[features]
+default = []
+tonic-reflection = ["dep:tonic-reflection"]