libtcgtpm: use bindgen in build.rs instead of bindgen-cli in Makefile

[stefano-garzarella]

We had several issues in our CI because we forgot to install bindgen-cli used in the libtcgtpm/Makefile to generate the TPM bindings.

Instead of using bindgen-cli (and then having as a requirement to have it installed), let's use bindgen in build.rs, this way the dependency is handled directly by cargo.

Let's also clean up the references to libtcgtpm/src/bindings.rs since bindings were already generated in the OUT_DIR.

Remove the reference to install bindgen-cli in the CI workflows, Documentation, and container image.

[stefano-garzarella]

Rust / Check unsafe blocks is failing because the base branch still requires bindgen-cli.
To make it pass, I can undo the change where I removed its installation for that workflow, but not sure if it makes sense or not, since after merging this PR, installing bindgen-cli is useless. @joergroedel WDYT?

[cclaudio]

LGTM

[cclaudio]

I was not able to reproduce the Rust / Check unsafe blocks issue. I fetched the PR and run

cargo clippy --workspace --all-features --exclude packit --exclude stage1 --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure --quiet -- -W clippy::undocumented_unsafe_blocks

Although that prints many unsafe warnings, the command exited with success (exit 0).

[stefano-garzarella]

I was not able to reproduce the Rust / Check unsafe blocks issue. I fetched the PR and run

Yeah, it's expected. We introduced a new CI workflow to avoid new unsafe blocks not documented.
That workflow checks out the base branch of the PR (e.g. main) and run that command to counts the number of unsafe blocks not documented, in order to compare them with the PR applied.

In this case I removed the bindgen-cli installation in the workflow, so that step fails.
I can put it back in that workflow, and maybe we can remove later, but when this PR will be merged, that should not be a problem anymore.