fix: Improve some missing cases with pop build spec #685
Description
Follows:
While adding this feature to Paseo CI (paseo-network/runtimes#285) I realized it's not supporting well CI integrations in codebases like Paseo. As it doesn't contain a folder purely called "runtime" anywhere, pop will correctly find the runtimes but prompt the user to pick one, which is a pain for CIs.
Additionally, we need to add args to allow modifying the "name" and "id" fields of the spec