[RFE] Make it easier to spin up custom local repos via the CLI

Currently, creating custom local repos involves manually creating a .profile file in /etc/solbuild/

e.g.

remove_repos = ['Solus']
add_repos = ['python3','Local','Solus']

# A local repo with automatic indexing
[repo.python3]
uri = "/var/lib/solbuild/local-python3"
local = true
autoindex = true

# A local repo with automatic indexing
[repo.Local]
uri = "/var/lib/solbuild/local"
local = true
autoindex = true

# Re-add the Solus unstable repo
[repo.Solus]
uri = "https://mirrors.rit.edu/solus/packages/unstable/eopkg-index.xml.xz"

It would be great if you could easily create a custom local repo from the cli. e.g. solbuild profile add myrepo /var/lib/solbuild/local-myrepo