cargo.tomls: Added Apache 2.0 to cargo.tomls

One of the checks done by cargo-deny is ensuring all crates have a valid
license. As the rust programs import each other, cargo.toml files
without licenses trigger the check. While I could disable this check
this would be bad practice.

This adds an Apache-2.0 license in the Cargo.toml files.

Some of these files already had a header comment saying it is an Apache
license. As the entire project itself is under an Apache-2.0 license, I
assumed all individual components would also be covered under that
license.

Signed-off-by: Derek Lee <derlee@redhat.com>

src/agent/Cargo.toml

@@ -3,6 +3,7 @@ name = "kata-agent"
 version = "0.1.0"
 authors = ["The Kata Containers community <kata-dev@lists.katacontainers.io>"]
 edition = "2018"
+license = "Apache-2.0"
 
 [dependencies]
 oci = { path = "../libs/oci" }

src/agent/rustjail/Cargo.toml

@@ -3,6 +3,7 @@ name = "rustjail"
 version = "0.1.0"
 authors = ["The Kata Containers community <kata-dev@lists.katacontainers.io>"]
 edition = "2018"
+license = "Apache-2.0"
 
 [dependencies]
 serde = "1.0.91"

src/agent/vsock-exporter/Cargo.toml

@@ -3,6 +3,7 @@ name = "vsock-exporter"
 version = "0.1.0"
 authors = ["James O. D. Hunt <james.o.hunt@intel.com>"]
 edition = "2018"
+license = "Apache-2.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html