feat: allow building for unsupported architecture
The hard check here has been prevented us (the RISC-V port) from utilizing pkgctl build
for a while. As long as the list (DEVTOOLS_VALID_ARCHES) isn't easily extendable, I think it's a better idea to allow building with a warning when specifying --arch
manually.
Also disables repository detection and --repo
check for unsupported architectures.
Edited by Felix Yan