To make the content transparent and facilitate changing the package,
this commit creates the deb used for testing programmatically instead of
embedding it as a base64-encoded blob directly.

Also, the entries not mentioned explicitly in the slice definition will not be
added to the report (e.g. copyright, parent directories). Additionally,
we have removed the Globbed option and simplified it.

This PR bumps the version of golang.org/x/crypto to v0.21.0.

Changes reflect the following operation:

go get -u golang.org/x/crypto

Resolves #126

This commit fixes three bugs regarding parent directory creation.

The first one is that implicit folders were overwriting the permissions
of explicit ones in slice definitions (e.g. slice A declares /foo/bar
and slice B /foo, if slice A was installed after B then the implicit
permissions of /foo from A would prevail.

The second one is that we were creating parent directories of optional
files which did not exist.

The third bug is that we were not using the permissions from the tarball
for parent directories if the path was a glob.

Remove noble from the CI because the tests break too often.
Will add them back when the release is stable.

Also drop the debug information from Spread output.

Syntactic sugar for adding essentials to all slices defined in the package without having to go one by one.

Fix reporting of paths that were selected by multiple slices, explicitly or via globs.

Streamline slicer.go moving some of the functionality to self-contained function / abstractions and adding comments where necessary. Most importantly, combine all maps that recorded information about paths into one (knownPaths, pathInfos and pathUntil) and record the information in the same place.

The paths with "mutable: true" property can be "mutated" with mutation
scripts. Thus, the files matching those paths may have a different size
and hash after the mutation scripts have been run. The report should
reflect these changes by updating the entries of the mutated paths.

Paths can also have the "until: mutate" property. This means that
those files are available until the mutation scripts have been run and
are not present in the final file system. Thus, they should not be part
of the report either.

This commit adds support for both -- it updates the changed properties
of mutated files and makes sure not to add report entries for
"until: mutate".

This commit adds the ``find`` command which can be used to query the
chisel releases for available slices.


Co-authored-by: Alberto Carretero <angelalbertoc.r@gmail.com>

Use strings.TrimPrefix for relative paths instead of strings.TrimLeft,
as the latter takes in a cutset instead of a prefix substring.