Allow overrides for comment on PR script (#219016)

## Summary

Culled from the work happening in
https://github.com/elastic/kibana/pull/212674.

Allows passing args to the `comment-on-pr.ts` script to specify
overrides, this is useful in cases where the build that want to invoke
this script would like to explicitly specify a value other than the
values it would previously have default to.

This allows to use the script in the following manner for example; 

```bash
ts-node .buildkite/scripts/lifecycle/comment_on_pr.ts \
	 --message "Linux headless chromium build started at: https://buildkite.com/elastic/kibana-migration-pipeline-staging/builds/309" \
	--context "chromium-linux-build-job-start" \
	--issue-number 212732 \
	--repository kibana \
	--repository-owner elastic \
	--clear-previous
```

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.buildkite/scripts/lifecycle/comment_on_pr.ts

@@ -33,15 +33,23 @@ const ALLOWED_ENV_VARS = [
   'GITHUB_PR_USER',
 ];
 
+interface CommentOnPRArgs {
+  messageTemplate: string;
+  context?: string;
+  clearPrevious: boolean;
+  issueNumber?: string;
+  repository?: string;
+  repositoryOwner?: string;
+}
+
 export function commentOnPR({
   messageTemplate,
   context,
   clearPrevious,
-}: {
-  messageTemplate: string;
-  context?: string;
-  clearPrevious: boolean;
-}) {
+  issueNumber,
+  repository: repositoryBase,
+  repositoryOwner,
+}: CommentOnPRArgs) {
   const message = messageTemplate.replace(/\${([^}]+)}/g, (_, envVar) => {
     if (ALLOWED_ENV_VARS.includes(envVar)) {
       return process.env[envVar] || '';
@@ -51,19 +59,26 @@ export function commentOnPR({
   });
 
   if (context) {
-    return upsertComment({ commentBody: message, commentContext: context, clearPrevious });
+    return upsertComment(
+      { commentBody: message, commentContext: context, clearPrevious },
+      repositoryOwner,
+      repositoryBase,
+      issueNumber
+    );
   } else {
-    return addComment(message);
+    return addComment(message, repositoryOwner, repositoryBase, issueNumber);
   }
 }
 
 if (require.main === module) {
-  const args = parseArgs<{
-    context?: string;
-    message: string;
-    'clear-previous'?: boolean | string;
-  }>(process.argv.slice(2), {
-    string: ['message', 'context'],
+  const args = parseArgs<
+    CommentOnPRArgs & {
+      'clear-previous'?: CommentOnPRArgs['clearPrevious'] | string;
+      'issue-number'?: CommentOnPRArgs['issueNumber'];
+      'repository-owner'?: CommentOnPRArgs['repositoryOwner'];
+    }
+  >(process.argv.slice(2), {
+    string: ['message', 'context', 'issue-number', 'repository', 'repository-owner'],
     boolean: ['clear-previous'],
   });
 
@@ -82,6 +97,9 @@ if (require.main === module) {
       typeof args['clear-previous'] === 'string'
         ? !!args['clear-previous'].match(/(1|true)/i)
         : !!args['clear-previous'],
+    issueNumber: args['issue-number'],
+    repository: args.repository,
+    repositoryOwner: args['repository-owner'],
   }).catch((error) => {
     console.error(error);
     process.exit(1);