rust: Refactoring and reduce API surface

Prepare pv & pv_core crates to be released on crates.io:
* Remove any unused API to stay flexible
* Remove utils dependency
* Move cli, tmpfile and version utilities to local utils crate
* Use the new utilities in the pv tools
* Rename Secret into Confidential to avoid confusion of Secret (now
  Confidential) and AddSecret requests.
* Move the uvsecret module out of the request module and change the name
  to secret.
* Cleanup dependencies
* Precise and correct minimal dependency versions
* Inline `Aes256Key::from_digest`

The cleanup ensures that the code also compiles with the dependencies
resolved to their minimal versions using:

$ cargo +nightly -Z minimal-versions update
$ cargo build

For more information refer to this blog post:
https://users.rust-lang.org/t/psa-please-specify-precise-dependency-versions-in-cargo-toml/71277/8

Signed-off-by: Marc Hartmayer <mhartmay@de.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

rust/pvapconfig/src/helper.rs

@@ -199,7 +199,7 @@ impl Drop for LockFile {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use pv_core::misc::TemporaryDirectory;
+    use utils::TemporaryDirectory;
 
     // Only very simple tests
 

rust/pvapconfig/src/main.rs

@@ -18,7 +18,7 @@ use config::{ApConfigEntry, ApConfigList};
 use helper::{LockFile, PATH_PVAPCONFIG_LOCK};
 use pv_core::uv::{ListableSecretType, SecretList};
 use std::process::ExitCode;
-use utils::release_string;
+use utils::print_version;
 
 /// Simple macro for
 ///   if Cli::verbose() {
@@ -58,11 +58,7 @@ macro_rules! on_error_print_and_exit {
 fn main() -> ExitCode {
     // handle version option
     if cli::ARGS.version {
-        println!(
-            "{} version {}\nCopyright IBM Corp. 2023",
-            env!("CARGO_PKG_NAME"),
-            release_string!()
-        );
+        print_version!(0, "2023");
         return ExitCode::SUCCESS;
     }