Add search_user Action

[jpavlav]

This PR includes the search_users action.

Example execution:

id: 6978b867fda9453e35e0ff71
action.ref: jira.search_users
context.user: st2admin
parameters:
  log_level: DEBUG
  query: [email protected]
status: succeeded (2s elapsed)
start_timestamp: Tue, 27 Jan 2026 13:06:47 UTC
end_timestamp: Tue, 27 Jan 2026 13:06:49 UTC
log:
  - status: requested
    timestamp: '2026-01-27T13:06:47.863000Z'
  - status: scheduled
    timestamp: '2026-01-27T13:06:47.937000Z'
  - status: running
    timestamp: '2026-01-27T13:06:47.959000Z'
  - status: succeeded
    timestamp: '2026-01-27T13:06:49.276000Z'
result:
  exit_code: 0
  result:
  - accountId: redacted_id
    accountType: atlassian
    active: true
    avatarUrls:
      16x16: https://avatar-management--avatars.us-west-2.prod.public.atl-paas.net/redacted_id
      24x24: https://avatar-management--avatars.us-west-2.prod.public.atl-paas.net/redacted_id
      32x32: https://avatar-management--avatars.us-west-2.prod.public.atl-paas.net/redacted_id
      48x48: https://avatar-management--avatars.us-west-2.prod.public.atl-paas.net/redacted_id
    displayName: Justin Palmer
    emailAddress: [email protected]
    locale: en_US
    self: https://place.atlassian.net/rest/api/2/user?accountId=redacted_id
    timeZone: America/New_York
  stderr: ''
  stdout: ''