Change the interface of the `export` command so that `PACKAGE_INFO` and
`SBOM` are proper, first-level sub-commands, rather than being implemented via
`export(EXPORT ... (PACKAGE_INFO|SBOM) ...)`. This brings consistency with the
`install` command and also simplifies argument parsing.
Update the documentation and test cases accordingly. Some of the
argument handling test cases are now rather gratuitous, and are removed,
which also improves consistency with the `install` tests.
Since commit 13c7bb5b0c (cmGeneratorExpression: Update strip function to
collect parsed expressions, 2025-04-08, v4.1.0-rc1~361^2~1), the logic
to strip generator expressions would error if the stripped expressions
were being collected and an expression without a `:` was found inside an
expression with a `:`. This resulted in an error when exporting a target
that contained such a generator expression in its link libraries or
compile definitions.
Address the error by checking whether the latest `$<` proceeded the
latest `:`.
Matthew Woehlke
Martin Duffy