[feature] Organization-independent firmware categories

[okraits]

Similar to configuration templates, it should be possible to create a firmware category without assigning it to a organization so that it can be used by several organizations.

[nemesifier]

The problem right now is that if I am not mistaken the organization information is only on the category and most of the other objects rely on that for multi-tenancy, so this can be done but would require changing a few parts of the code.