fix(actions): evaluate each ${{ }} part on its own (#38754)

[silverwind]

Backport of #38754

Every ${{ }} part was spliced as raw text into a synthesized format('...', <raw>) call and re-parsed, so unbalanced parentheses restructured the whole expression:

run-name: ${{ 1) && (2 }}          # panicked, aborting workflow parsing for the push
if: ${{ 1 }} ${{ 0) && (0 }}       # silently skipped the job
runs-on: ${{ nosuchcontext.x }}    # silently queued the job against the label ""

One scanner shaped like GitHub's template reader now splits every value and each part is evaluated on its own, so nothing builds an expression out of text. A part that fails is an error instead of an empty string.

expressionCallsFunction is self-contained here, since this branch has no expressionsMatch to build it on. That makes github.com/rhysd/actionlint a direct dependency, which it already is on main.