cargo-update-recipe-crates.bbclass: add a class to generate SRC_URI crate lists from Cargo.lock

For better or worse, more and more rust components are appearing that do
not include their dependencies in tarballs (or git trees), and rely on cargo
to fetch them. On the other hand, bitbake does not use cargo (and quite possible
won't ever be able to), and relies on having each item explicitly listed in SRC_URI
with a crate:// prefix. This however creates a problem of both making such lists in
the first place and updating them when a recipe is updated to a newer version.

So this class can be used to perform such updates by implementing a task that does it;
the next commit shows the outcome for python3-bcrypt (which has been tested to work
and produce a successful build).

Note: the python script relies on tomllib library, which appears in Python 3.11 and
does not exist in earlier versions - I've tested this by first updating python to 3.11-rc2
in oe-core.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>