Add "Create new Azure Container Registry" option to the Build Image in Azure registry pick

[Copilot]

The "Select registry" step of Azure Container Registry: Build Image in Azure... offered only existing registries, with no way to create a new one — unlike the push-image flow. The step relied on a bare registryExperience call rather than CreatePickAcrPromptStep.

Changes

• Extracted pickAcr helper (commands/registries/azure/pickAcr.ts): given a subscription node, lists its ACRs plus a + Create new Azure Container Registry... item; on selection it runs createAzureRegistry and returns the created node.
• scheduleRunRequest: swapped the direct registryExperience registry pick for subscriptionExperience → pickAcr, so "Build Image in Azure..." now surfaces the create-new option.
• CreatePickAcrPromptStep (push-image flow): refactored to delegate to pickAcr, removing duplicated pick/create logic and keeping both flows consistent.

pickAcr returns UnifiedRegistryItem<AzureRegistry>, which is assignable to CommonRegistry for the push flow and yields an AzureRegistryItem wrappedItem for scheduleRunRequest — no unsafe casts needed.

export async function pickAcr(context: IActionContext, subscriptionNode: UnifiedRegistryItem<AzureSubscriptionRegistryItem>): Promise<UnifiedRegistryItem<AzureRegistry>> {
    const acrs = await ext.registriesRoot.getChildren(subscriptionNode) as UnifiedRegistryItem<AzureRegistry>[];
    const picks = acrs.map(acr => ({ label: acr.wrappedItem.label, data: acr }));
    picks.push({ label: vscode.l10n.t('$(plus) Create new Azure Container Registry...'), data: 'create' });
    // ...create-or-return selected registry
}

This deliberately avoids converting scheduleRunRequest into a full wizard (noted in the issue as conflicting with #112).

Notes for reviewers

Type-check/build could not be run in the sandbox — pnpm install failed with DNS errors (ENOTFOUND packagefeedproxy.microsoft.io), so TypeScript never installed. Please run pnpm build/pnpm lint to confirm.

• Fixes There is no "+ Create new Azure Container Registry..." in "Select registry" option when executing "Build Image in Azure..." command #230

[bwateratmsft]

Ideally we would convert this whole thing into a wizard...and then just reuse CreatePickAcrPtomptStep

[bwateratmsft]

@copilot see about doing this conversion...

[Copilot]

Done in 3d237d2: scheduleRunRequest is now an AzureWizard flow, and ACR selection now reuses CreatePickAcrPromptStep (via a shared wizard context type) instead of calling a separate direct picker path.