Relax restrictions in platform check when creating security advisories

[javihernandez]

When we create a security advisory only present in AlmaLinux, we need to indicate the target platform. This is, where the security advisory will be released to. Right now, there is a restriction in frontend that prevents us to add errata packages that were built for a different platform than the one selected when creating the security advisory. In general, this is a good idea, this way, we prevent introducing potential wrong data into our erratas. However, in some situations and as an example, the packages built for AlmaLinux Kitten 10 can be released directly into AlmaLinux 10, and we need to also allow this behavior when creating security advisories.

Our platform definitions already describe this relationship between platforms, using the compatible_release_platforms field.

1. We need to use this data to figure out whether packages built for one platform can be released into another platform and allow adding them in such case
2. If the platforms aren't "release compatible", then we need to avoid the user to add such packages to the security advisory and show the error to the user as we do right now
3. As a sanity check, when adding packages from a "release compatible" platform, we also show a warning to the user indicating that the packages added were built for a different platform, just in case