login: suggested issuers

[angelo-v]

WIP to implement part of #21 - using a modal dialog instead of prompt allows browser's built-in autocomplete to be used and provided platform for further features

• [x] Create modal in pos-login & display modal on click - now waiting on #23
• [x] Duplicate functionality of getIdpUrl, i.e. a single input textbox with a default value
• [x] Style pos-login-form
• [x] Tests have been written
  • [x] all new code is covered by unit tests
  • [x] Add test for pos-login-form
  • [x] Edit tests for pos-login
    • [x] pos-login.spec.tsx
    • [x] pos-login.integration.spec.tsx
  • [x] the happy path of a new feature is covered by an end-to-end test
  • [x] Add new e2e test in https://github.com/pod-os/PodOS/tree/main/apps/tests
  • [x] manual explorative tests have been performed
• [x] all dependencies are updated to the latest patch version at minimum
  • Done upstream
• [x] the CI pipeline passes
• [x] documentation is up-to-date
  • [x] TSDoc style comments on important functions, properties and events
    • Documented onIdpUrlSelected event
  • [x] stories for new PodOS elements have been added to storybook
    • [x] No changes required to https://github.com/pod-os/PodOS/blob/main/storybook/stories/login/1_pos-login.stories.mdx
  • [x] Readme.md files of PodOS elements have been re-generated
  • npm run build in elements
  • [x] architectural decisions are documented as an ADR
  • No new architectural decisions
  • [x] Changelogs are updated according to Keep a Changelog
• [x] Possibly rename onIdpUrlSelected event

Edited 29 Jul to reduce scope of this PR. See #21 for backlog checklist

[angelo-v]

supersedes https://github.com/pod-os/PodOS/pull/22