Allow the manifest variables, defined via mpp-vars, to be used from
within the mpp blocks. For this template strings are used, where
variables are marked via `$`. We cannot use the `mpp-format` logic
easily there, since that is processed after other mpp directives
have been processed.
As a result remove the built-in substitution from support from dnf
dep-solving, since we had to post-process the resulting urls with
variable substitution afterwards. Now that is covered with this
more generic mechanism.
Introduce a helper method that will return the mpp node of a given
name or `None` if it does not exist. Delete it from the parent
dictionary if it did.
Reorder the typing imports as well to be sorted below the non-
`from` imports.
It is now possible to define a partition layout via `mpp-define-image`.
The defined layout is actually written to a temporary sparse file and
read back via `sfdisk`, so that all partition data like `size` and
`start` include actual padding and such. The `image` variable will be
defined with `size` and `layout` keys, the latter containing the
partition layout data. It can be accessed via the "String expansion"
mechanism.
Previous versions of mpp would already set the arch and basearch
substitution, which would work for dep-solving itself, but not
properly re-write the resulting URLs which means that the manifest
was broken. Fix this by properly replacing the substitutions in
the URL. Also support official 'releasever' substitution.
Instead of passing dictionaries around that are inconvenient to
use in code and even more in the `mpp-format-*` directives, use
a simple class to represent package information. Use that in
the `pkginfo` dict that can be accessed via `mpp-format-*`. Use
the `evra` property instead of string manipulation in the
`fedora-boot.mpp.json` and `-ostree-bootiso.mpp.json` manifest.
