This puts all static functions in geometry node files into a new
namespace. This allows using unity build which can improve
compile times significantly (P2578).
* The name space name is derived from the file name. That makes
it possible to write some tooling that checks the names later on.
The file name extension (`cc`) is added to the namespace name as
well. This also possibly simplifies tooling but also makes it more
obvious that this namespace is specific to a file.
* In the register function of every node, I added a namespace alias
`namespace file_ns = blender::nodes::node_geo_*_cc;`. This avoids
some duplication of the file name and may also simplify tooling,
because this line is easy to detect. The name `file_ns` stands for "file
namespace" and also indicates that this namespace corresponds to
the current file. In the beginning I used `node_ns` but `file_ns` is more
generic which may make it more suitable when we want to use unity
builds outside of the nodes modules in the future.
* Some node files contain code that is actually shared between
different nodes. For now I left that code in the `blender::nodes`
namespace and moved it to the top of the file (couldn't move it to
the bottom in all cases, so I just moved it to the top everywhere).
As a separate cleanup step, this shared code should actually be
moved to a separate file.
Differential Revision: https://developer.blender.org/D13330
1df8abff25