feat: add pagination to alerts and messages endpoints

[yrobla]

Modify the API to add pagination to those endpoints, to be able to render faster in the browser

Closes: #1020

[peppescg]

LGTM 🚢

[alex-mcgovern]

Copying this from Slack, so it doesn't get buried in discussion.

In early testing, we all saw crashed in the frontend — our Table implementation expects that chat_id on each object in the list of messages is unique — I am seeing some duplication in the response, e.g.

curl -s "http://localhost:8989/api/v1/workspaces/default/messages?page=1&page_size=50" | jq -r '.data | map(.chat_id)'
[
  "5c7d8bc9-716d-4106-aafc-890564cb212f", # dup #1
  "cf50f1e5-4064-42e5-bf26-15249dc78e46",
  "0fdd2a27-821a-427f-8bf6-cca39bfde838",
  "5ac437ff-6b1c-4aa4-b276-d43bce33f28e",
  "aa85b6a5-423a-4cd0-a27f-51088b5fe30c",
  "aadeadbb-43e0-4c20-9565-f0e5599596c7", # dup #2
  "00916b98-a3d3-424d-8e1f-d24da8c51afc",
  "3fae75e6-e32b-4d24-9856-f0b0cc88785e",
  "5c7d8bc9-716d-4106-aafc-890564cb212f", # dup #1
  "f397d262-07f6-4724-ac94-f0d45a09eb01",
  "9aa71a60-ab7f-4d76-b9a3-13ec25d65661",
  "aadeadbb-43e0-4c20-9565-f0e5599596c7", # dup #2
  "131a028d-9e00-4565-8796-40cef7cd3b83",
  "88a40a5f-dd98-46eb-bf53-7422853629c0"
]

[yrobla]

closed in favor of @alex-mcgovern PR