Query deploy keys by matching title

What does this MR do and why?

• Extend DeployKeysWithWriteAccessFinder to check if title contains some term
• We start making these queries in the next MR here: !145976 (merged)

New queries

https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/26637/commands/83355

SELECT "keys".*
FROM "keys"
INNER JOIN "deploy_keys_projects" ON "keys"."id" = "deploy_keys_projects"."deploy_key_id"
WHERE "keys"."type" = 'DeployKey'
  AND "deploy_keys_projects"."project_id" = 13083
  AND "deploy_keys_projects"."can_push" = TRUE
  AND "keys"."title" ILIKE '%sync%'

MR acceptance checklist

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Related to #432494 (closed)

app/finders/autocomplete/deploy_keys_with_write_access_finder.rb

@@ -15,7 +15,7 @@ def execute(title_search_term: nil)
 
       raise Gitlab::Access::AccessDeniedError unless current_user.can?(:admin_project, project)
 
-      relation = project.deploy_keys.merge(DeployKeysProject.with_write_access)
+      relation = DeployKey.with_write_access.in_projects(project)
       relation = relation.fuzzy_search(title_search_term, [:title]) if title_search_term.present?
       relation
     end