Opt-in Mode for prediction results

Start by reading related issues #3581, #3607, and #2504, then inspect how prediction view options and key handlers are currently exposed. Done should include an opt-in prediction setting, a defined key-triggered ListView flow, and agreed behavior for accessibility and predictor timeouts.

Prerequisites

• Write a descriptive title.

Description of the new feature/enhancement

It may eventually make sense to have a predictor option to make listview results be "asked" for by the user or triggered by a keyhandler. It could solve two problems:

1. Accessibility, (after we fix screen reader issues currently), it would be easier to navigate prediction results via screen reader if the user is able to explicitly opt-in to getting the results and have some kind of indicator that prediction results are available.
2. Off box calls to predictors - since the user is opting in to getting predictor results, we could allow for a longer time out as the user is specifically asking for this

Proposed technical implementation details (optional)

Include a PSreadLine option for a getting predictions opt in. I.e something like

Set-PSReadLineOption -PredictionViewStyle OptIn

and then when a user types something, they can press a key to get ListView to render based on currently typed content:

PS>Get-
<Presses F5>
<-/9>                                                                   <History(3) Az Predictor(6)>
> Get-alias                                                                                [History]
> Get-ChildItem                                                                            [History]
> Get-ChildItem | Show-ObjectTree                                                          [History]
> Get-AzSubscription                                                                  [Az Predictor]
> Get-AzResourceGroup                                                                 [Az Predictor]
> Get-AzRoleAssignment -Scope '/subscriptions/00000000-0000-0000-0000-00000000000000… [Az Predictor]
> Get-AzVM                                                                            [Az Predictor]
> Get-AzStorageAccount -Name 'ContosoStorage' -ResourceGroupName 'ContosoResourceGro… [Az Predictor]
> Get-AzKeyVaultSecret -Name 'secret*' -VaultName 'keyvault01'                        [Az Predictor]

Some clearer naming may be required.. 😄

Related issues: #3581 #3607 #2504