run-make: vendor cargo dependencies or external dependencies within the tests

[jieyouxu]

• tests/run-make/thumb-none-qemu
• tests/run-make/x86_64-fortanix-unknown-sgx-lvi
• tests/run-make/thumb-none-cortex-m (uses git clone too)

These tests use cargo to build crates but they have external dependencies -- this makes their pass/fail status conditioned on internet connectivity which does not seem ideal (and also if it's not pinned and it can become awkward from breakages..)

We should investigate if we could vendor the external deps or otherwise make them locally available to make the test outcomes more reproducible.

[tdittr]

For reference the this was discussed for thumb-none-qemu and thumb-none-cortex-m at an embedded WG meeting: rust-embedded/wg#783 (reply in thread)