SKA: Extract list of Kibana solutions into a dedicated package (elastic#213353)

## Summary

The intent is to have a centralised place to store the list of Kibana
solutions and serverless project types.
To that end, this PR creates a `@kbn/projects-solutions-groups` package.
It also adds the new solution type `'chat'`.

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

Author: gsoldevila

.buildkite/scripts/steps/cloud/purge_projects.ts

@@ -12,13 +12,16 @@ import axios from 'axios';
 import { getKibanaDir } from '#pipeline-utils';
 
 async function getPrProjects() {
-  const match = /^(keep.?)?kibana-pr-([0-9]+)-(elasticsearch|security|observability)$/;
+  // BOOKMARK - List of Kibana project types
+  const match = /^(keep.?)?kibana-pr-([0-9]+)-(elasticsearch|security|observability|chat)$/;
   try {
+    // BOOKMARK - List of Kibana project types
     return (
       await Promise.all([
         projectRequest.get('/api/v1/serverless/projects/elasticsearch'),
         projectRequest.get('/api/v1/serverless/projects/security'),
         projectRequest.get('/api/v1/serverless/projects/observability'),
+        // TODO handle the new 'chat' project type - https://elastic.slack.com/archives/C5UDAFZQU/p1741692053429579
       ])
     )
       .map((response) => response.data.items)
@@ -47,11 +50,13 @@ async function deleteProject({
   id,
   name,
 }: {
-  type: 'elasticsearch' | 'observability' | 'security';
+  // BOOKMARK - List of Kibana project types
+  type: 'elasticsearch' | 'security' | 'observability' | 'chat';
   id: number;
   name: string;
 }) {
   try {
+    // TODO handle the new 'chat' project type, and ideally rename 'elasticsearch' to 'search'
     await projectRequest.delete(`/api/v1/serverless/projects/${type}/${id}`);
 
     execSync(`.buildkite/scripts/common/deployment_credentials.sh unset ${name}`, {

.buildkite/scripts/steps/serverless/deploy.sh

@@ -9,6 +9,7 @@ KIBANA_IMAGE="docker.elastic.co/kibana-ci/kibana-serverless:pr-$BUILDKITE_PULL_R
 
 deploy() {
   PROJECT_TYPE=$1
+  # BOOKMARK - List of Kibana solutions
   case $PROJECT_TYPE in
     elasticsearch)
       PROJECT_TYPE_LABEL='Elasticsearch Serverless'