Support `rgb(R G B)` (without commas) as valid color format
#### Steps to reproduce:
- Open [this](https://gitlab.com/openingdesign/milwaukee_st_4429/-/blob/6e1e3682c2a7d968a2797bfc7a274a695046d704/Models/BlenderBIM/sheets/A700%20-%20DETAILS.svg) svg in Inkscape 1.3
- Expect to see patterns rendered like..

- instead see...

####
#### What should have happened?
* would expect the pattern to show correctly.
#### Inkscape Version and Operating System:
- Inkscape Version: 1.3
- Operating System: Windows
- Operating System version: 10
issue