add an new api for listing all projects

[nisainan]

When we are building our own configuration center, we need to display all the currently configured projects, so this interface is added. But currently only supports Mongo driver, we hope to improve the implementation of etcd, thank you very much!

[tianxiaoliang]

please resolve the conflicts

[nisainan]

i am sorry that this pr has some conflicts with latest main branch, now i fix it,please run workflows again to ckeck. thanks