Add "always" option to createOnPublishBranch setting

[Copilot]

The githubPullRequests.createOnPublishBranch setting previously supported only "never" and "ask" options. Users requested an "always" option to automatically create PRs on branch publish without prompting.

Changes

• Configuration (package.json): Added "always" enum value and description reference
• Localization (package.nls.json): Added description string for the "always" option
• Implementation (src/extension.ts): Updated git.onDidPublish handler to:
  • Accept 'always' in type definition
  • Auto-create PR when set to "always", skipping the prompt dialog
  • Preserve existing behavior for "ask" and "never"

Behavior

// Setting: "always" → Creates PR automatically on publish
// Setting: "ask"    → Shows dialog (default, unchanged)
// Setting: "never"  → No action (unchanged)

The logic extracts the setting value once, returns early on "never", auto-creates on "always", and falls through to the existing prompt flow for "ask".

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add "always" option to "Create On Publish Branch" setting</issue_title>
<issue_description>Currently, "Create On Publish Branch" setting only has options "never" or "ask". It would be great to have an "always" option as well.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add "always" option to "Create On Publish Branch" setting #6123

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