Bump to odlparent-9.0.0/yangtools-7.0.1-SNAPSHOT

Bump to odlparent-9.0.0/yangtools-7.0.1-SNAPSHOT

Aside from the usual mechanical updates, we need to also rewrite
mdsal-binding-generator-impl, as its mechanics relied completely on
TypeDefinition.getPath(), which is no longer available.

The rewritten component is a wee bit more navigable, making a number of
deficiencies clearly visible. These are marked as FIXMEs for future
improvements.

One such problem arises when we attempt to create a derived type from an
enumeration: here we ended up generating an empty DTO rather than
properly specializing the type. Attempting to retain compatibility would
be fruitless, as it would violate a number of method signatures.

Furthermore leafref resolution is made stricter, requiring that
references actually point to a leaf, not to a random location -- which
was true in abstract-topology@2013-02-08.yang test model.

Another change revolves around nested union types. These previously
ended up being flattened in the class hierarchy, i.e. siblings of the
generated type and enclosed in the top-level type. Refactored code
structure is showing this is inconsistent, as bits/enums end up not as
siblings, but rather normal enclosed types.

This patch leaves a bit of dead code, deactivated test cases as well as
a few uncaught codegen regressions. These will be rectified by follow-up
patches.

JIRA: MDSAL-503
Change-Id: I40c445aa1d3f79fd55f6e8007db1259d9a09c8d8
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>