docwriter/gjs: ignore nodes without a namespace

g-ir-compiler ignores them too, and they cause a crash, so whatever.
docwriter/gjs: report arrays of (u)int8 and GBytes as ByteArray

The ByteArray class is special in gjs, it's not a normal Array,
so make sure it's flagged as such.
docwriter/gjs: add support for shadowed function names

If a function is shadowed, omit it from the documentation, and
if a function shadows, uses the new name.
docwriter/gjs: include non GObject instantiatable types

Support for fundamental types was just merged in gjs, so just
filter out GParamSpec subclasses (because there is only one
class in gjs)
docwriter/gjs: fix constructors

We should only look at introspectable constructors when resolving
the default and zero args. Also, a disguised structure or one
with zero fields can't be allocated directly.

In addition, restore availability of all constructors, because
we need a page to document the default one, and because some classes
have problems with GObject construction.
docwriter: don't ignore disguised structures

Unless they have no methods, static methods and constructors
(because then they are useless)
Fixes GLib.BookmarkFile, GLib.PatternSpec and probably others.
maintransformer: don't pair methods if the symbol prefix does not match with a final underscore

In cases like g_resources_register() and gdk_events_get_angle(),
the c_symbol_prefix of the first parameter (resp. g_resource and
gdk_event) is a prefix of the symbol, but the next character is
not _, so that should not be considered a method.
For backward compatibility reasons, we still generate one, but
then it's not included in the documentation (because of moved_to)
docwriter: extend the "node without namespace" filtering to all languages

As the comment says, it's an AST bug, the structure there cannot
be reasonably represented in gobject-introspection, and it makes
the tests for C and Python crash, so whatever.
docwriter/Gjs: include static methods in the enum page

Switch enum from a topic to a guide page, and include links to
all static methods.
girparser: fix parsing of enum methods

Make sure to set the parent of the function
docwriter: improve xrefs

If a xref points to a node that was not visited, because it
was not introspectable, don't assume it has no parent. Instead,
try to fetch the parent from the node directly.
This is still wrong (the xref points nowhere because no page is
generated), but it looks less wrong.
If OTOH a xref points to a different namespace, generate the
link directly, because yelp-build is not capable of translating
it.
doctool: update tests