chore: Simplify create-vsix inputs and improve branch resolution

[TwitchBronBron]

What

• The workflow_dispatch now takes a single pr input: a PR number (for this repo), a full PR URL (for any repo), or a branch name — replacing the separate branch/pr/repo inputs.
• scripts/create-vsix.ts now resolves each project's build source with this priority:
  1. rokucommunity branch attached to an open PR
  2. the originating fork owner's same-named branch attached to an open PR (clones the fork)
  3. rokucommunity branch without a PR
  4. master
• The PR comment now includes a Built from: section listing exactly which source each of the 5 projects was built from.

Why

• Fork PRs previously built silently from master (the fork's branch never exists on the rokucommunity clone), producing a vsix with none of the PR's changes. Now the fork branch is used — but only when it belongs to the same owner as the originating PR and is attached to an open PR, so an unrelated fork's patch-1 can never leak into a build.
• Upstream repos no longer need to pass branch/repo — just the PR URL.

Rollout

⚠️ Must merge together with the matching PRs on the dispatcher repos (brighterscript, roku-debug, roku-deploy, brighterscript-formatter, logger, roku-test-automation) — workflow_dispatch rejects unknown inputs, so the old branch/repo payloads fail once this merges.

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