`azdev setup` to also provide folder option for --repo parameter

azdev setup expects --repo parameter to be a git-repository

We would like the `azdev setup` to be able to accept a folder(not necessarily a git repo).

We have multiple versions of az cli extension for our service (networkcloud) and we would like to setup/install a specific version at a time.

```
=======================
| Azure CLI Dev Setup |
=======================

Azure CLI:
PyPI

Azure CLI extension repos:
/__w/1/s

Azure CLI extensions:
/__w/1/s/cli-ext/v20230501preview/ext/src/networkcloud
/__w/1/s/cli-ext/v20221212preview/ext/src/networkcloud

Installing packages
=====================

Upgrading pip...
Installing `azure-cli`...
Installing `azure-cli-testsdk`...
Adding extension '/__w/1/s/cli-ext/v20230501preview/ext/src/networkcloud'...
Adding extension '/__w/1/s/cli-ext/v20221212preview/ext/src/networkcloud'...

Elapsed time: 2 min 18 sec

Finished dev setup!
=====================

[
{
"install": "",
"name": "networkcloud",
"path": "/__w/1/s/cli-ext/v20230501preview/ext/src/networkcloud"
},
{
"install": "",
"name": "networkcloud",
"path": "/__w/1/s/cli-ext/v20221212preview/ext/src/networkcloud"
}
]
## pinning to specific version due to failure observed in urllib3.connectionpool
Found existing installation: urllib3 1.26.16
Uninstalling urllib3-1.26.16:
Successfully uninstalled urllib3-1.26.16
Looking in indexes: https://build:***@pkgs.dev.azure.com/msazuredev/AzureForOperatorsIndustry/_packaging/AzureForOperatorsIndustry_PublicPackages/pypi/simple
Collecting urllib3==1.25.8
Downloading https://pkgs.dev.azure.com/msazuredev/c0b6323e-5225-48c2-85df-819f77430aea/_packaging/c900f78d-fdf9-4052-9954-36e35dc9bcb9/pypi/download/urllib3/1.25.8/urllib3-1.25.8-py2.py3-none-any.whl (125 kB)
```

Inizia dal comando azdev setup e dalla gestione del relativo argomento --repo; esamina come viene convalidato il valore attuale e come vengono individuati i percorsi delle estensioni. Il lavoro è completato quando --repo accetta una cartella ordinaria, non solo un repository Git, e setup può installare da quella cartella la versione prevista dell'estensione.

Scritto dal modello di indicizzazione a partire dal testo della issue.