ci: refactor CI files

Mostly rename file and variable names to be more consistent. This makes
it easier to locate them in the "Actions" tab on github.

.github/scripts/reviewers_remove.js

@@ -0,0 +1,16 @@
+module.exports = async ({ github, context }) => {
+  const requestedReviewers = await github.rest.pulls.listRequestedReviewers({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    pull_number: context.issue.number,
+  });
+
+  const reviewers = requestedReviewers.data.users.map((e) => e.login);
+
+  github.rest.pulls.removeRequestedReviewers({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    pull_number: context.issue.number,
+    reviewers: reviewers,
+  });
+};