`az extension add` : Ability to fail installation (or upgrade) if latest version cannot be installed

**Related command**

`az extension add`

**Is your feature request related to a problem? Please describe.**

`az extension add --upgrade` installs or upgrades an extension. It does a compatibility check with the current version of `azure-cli` and installs an older version if `az` is old and if the latest extension version is not compatible with old `az` version.

**Describe the solution you'd like**

I'd like to have an option or flag to always install the latest version of extension. If the install or upgrade is not possible due to compatibility-issues, we should **fail the operation** instead of installing an older version.

**Describe alternatives you've considered**

**Additional context**