Bug 16407

The documentation that you can use any prefix for SPDX variable is wrong, since it isn't supported. One of the examples in https://docs.yoctoproject.org/dev/ref-manual/variables.html#term-SPDX_INVOKED_BY:

```
MY_COMPANY_name = "Acme Corp"
MY_COMPANY_type = "organization"
SPDX_IMAGE_SUPPLIER = "MY_COMPANY"
SPDX_SDK_SUPPLIER = "MY_COMPANY"
```

From looking at the code, <PREFIX> isn't used at all in most of those variables, only the (taken from new_agent function in meta/lib/oe/sbom30.py):

- <PREFIX>_name
- <PREFIX>_type
- <PREFIX>_import
- <PREFIX>_comment
- <PREFIX>_id_* (all of the options in oe.spdx30.ExternalIdentifierType.NAMED_INDIVIDUALS) - only _email is mentioned in documentation
- <PREFIX>_ref - not mentioned at all, works "somewhat" like what documentation says setting prefix does.

The issue applies to (either mentioned directly, or by linking to, usually, SPDX_IMAGE_SUPPLIER):
- SPDX_IMAGE_SUPPLIER
- SPDX_PACKAGE_SUPPLIER
- SPDX_SDK_SUPPLIER
- SPDX_INVOKED_BY
- SPDX_ON_BEHALF_OF

The patch that I posted (https://lists.openembedded.org/g/openembedded-core/topic/patch_v2/120910416) tried to change the code to match the documentation but based on the Joshua comment: https://lists.openembedded.org/g/openembedded-core/message/244245 it's the documentation that needs to be fixed not the code.

Steps to reproduce the issue:
- try to use documented example (the one I mentioned in the beginning) and check if generated SPDX contains `Acme Corp`