GitHub Action: deploy-center changed

Runs deploys changed --json on a Linux runner and gives you the result as outputs. It deploys only when the workflow sets deploy: true, and then it runs deploys deploy-changed --yes for the projects that deploy from this repository (input repo), not for every project the tokens can see.

- uses: Pschmetzer/deploy-center/integrations/action@<tag or commit SHA>
  id: dc
  with:
    vercel-token: ${{ secrets.VERCEL_TOKEN }}
    render-api-key: ${{ secrets.RENDER_API_KEY }}
    repos-json: ${{ vars.DEPLOYS_REPOS_JSON }}   # your ~/.config/deploys/vercel-repos.json
    # deploy: true                               # only where a person asked for it
- run: echo "${{ steps.dc.outputs.count }} waiting: ${{ steps.dc.outputs.names }}"

Pin the action to a release tag or a full commit SHA, not to main. Give the job a timeout-minutes: with a wrong Render key the CLI currently does not come back.

Input	Default
`deploy`	`false`	`true` starts the deploys. Any other value only reports.
`repo`	`github.repository`	With `deploy: true`, only projects whose repo is this one are started (`owner/name`, or `host/group/name` for GitLab; case does not matter). From an "ops" repo, name the app repo here. `*` starts every changed project in every repo (what `deploy: true` did in 0.9.1 and earlier).
`vercel-token`	none	Read by the Vercel CLI (`VERCEL_TOKEN`). Leave it empty if you have no Vercel projects.
`vercel-team`	none	The team id, if the token sees several teams.
`render-api-key`	none	Leave it empty to skip Render.
`github-token`	`github.token`	Reads branch heads and pull requests. Other private repos need a token that can read them.
`repos-json`	none	The content of `vercel-repos.json`. Without it, Vercel projects whose Git connection is off are never counted.
`vercel-cli-version`	`65.12.1`	Installed only when no `vercel` is on the runner.

Output
`count`	How many projects have changes.
`names`	Their names, comma-separated.
`projects`	The JSON array from `deploys changed --json`.
`started`, `failed`	How many deploys were started, and how many failed to start.
`deployed`	`true` when every start succeeded and every state could be read. Otherwise the step fails, after writing the outputs.

The outputs count, names and projects still list every changed project the tokens see; only the deploy is limited to repo. How: every other project goes into ignored.json of the run's own config folder (in RUNNER_TEMP, gone after the job), and deploy-changed --json is asked first what it would start. The step fails and starts nothing when the project list cannot be read, when a name exists in this repo and in another one (deploying it would start both), or when anything outside repo would still be started.

Each step also writes a short summary to the job page. When some project's state cannot be read, the step warns and leaves that project out. It is never counted as up to date.

The example examples/deploy-on-marker.yml deploys only when the last commit of a push says [deploy], or when someone runs the workflow by hand and ticks the box. For a time-based deploy, see ../../examples/daily-deploy.yml.

Not tested yet: a run on GitHub's runners against real accounts. The steps' scripts are tested locally with a stand-in deploys (integrations/tests/run.sh).