azdev setup does not allow specific path to hold my extension within my repo

After cloning the `azure-cli` and `azure-cli-extensions`, I want to develop and place my extension in my existing repo, within a specific folder.

If I run `azdev setup --cli /home/joalmeid/tre-cli/azure-cli --repo /home/joalmeid/tre-cli/AzureTRE/cli` I'll get an error stating that the repos is invalid.

If I run `azdev setup --cli /home/joalmeid/tre-cli/azure-cli --repo /home/joalmeid/tre-cli/AzureTRE` which is the repo root, I will be successful, and when afterwards If I run `azdev extension add ` I'll scaffold the extension code in `src/` which is not my desired behavior.