* AccountPolicyService

Expects product.json value 'defaultAccount.chatUrl'

* tidy up reading token

* Register 'extensionConfigurationPolicy' for relevant configuration

Also needed to move some types around to use IPolicy

* for demo set convention that accountpolicyservice looks at Copilot* policy

* register extension policy 'configurationExtensionPoint'

* rename entitlements

* implement previewFeature in IPolicy

* unused import

* add type for IPolicy.defaultValue?

* always initialize AccountPolicyService in desktop.main

* remove unused import

* make defaultAccountRequests in parallel

* initialization of defaultACcount in accountPolicy

* initialize policy in multiplexservice, only update when needed, and detect duplicates

* Apply suggestions from code review

Co-authored-by: Sandeep Somavarapu <sasomava@microsoft.com>

* consistent naming in defaultAccount

* fix type in PolicyDefinition

* formatting missed from gh code review commit

* simply insertion of extensionConfigurationPolicy

* Add preview policy

* update policy

* reload fixes

* update distro (https://github.com/microsoft/vscode-distro/pull/1105

)

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Co-authored-by: Sandeep Somavarapu <sasomava@microsoft.com>