Added scenario to handle enable/disable of setup button. Also button text changed based on the scenario that either setup/update

[msivasubramaniaan]

This PR helps to handle the below scenarios, and it would be nice to have as a user perspective.

1. Button text changed between Setup/Update based on the installation status of the models
2. If user selects the model which currently used then disabled the button

PFA

[deboer-tim]

Disabling the button when there's no change is nice, but if I don't realize that I've selected the current options it could be confusing why the button won't enable. IMHO either the button text needs to change as well, or replace the button with a label. Just something to indicate 'these are the current settings/configuration'.

[fbricon]

I'm dubious about this proposed change. The behavior is inconsistent between:

• you select something that's already in config.json : button not disabled
• you select something that's now in config.json : button disabled

I don't want to disable the button if the models are identical to what's in config.json, as I regularly rerun the setup because specific settings, other than the model id (context length, maxTokens ...) can change between extension builds, so I need to apply those changes.