Display a notification to install sfdx when bin isn't available

[AllanOricil]

Currently, users have to install sfdx extensions and sfdx separately opening a terminal, or manually downloading an executable, as described here. This made me think what if after installing the official extension pack, a vscode notification appears saying "Hey, sfdx could not be identified in your computer. Would you like it to be installed?" Upon clicking on "yes", sfdx is installed using npm, for the current user session only. The same automation could be done for setting up Java, since it is a dependency in one of the extensions. This will ease local dev env setup.

This feature can be combined with this other one: #5352

There could exist a new extension that would be part of the official extension package to handle this and the above feature. Maybe you can call it "sf-cli-manager"

[AllanOricil]

If there are many other requirements to make the extension pack to work, maybe you can create a webview with setup steps to guide users to install all the necessary dependencies:

step 1 -> step 2 -> step 3...

It is an onboarding automation to ease the setup