[Draft] Implementing a new branding service

[abbyhu2000]

Description

This PR is a rough draft that creates a new branding service to handle all custom branding related logic to reduce duplication. I have verified it works for all logo occurrences including default mode and dark mode. It does not include any tests yet.

Here is one potential implementation:

1. On the server side: A new branding service is created. Previously the logics including retrieving branding configs from yml file, branding validation, http agent logic to solve ssl failure are all stored in the rendering service. Currently the newly created branding service will handle all those logic and the rendering service will just call the branding service to get all the branding information.
2. Previously the branding info is passed in the metadata, currently it will be passed separately from the metadata. It will be rendered as 'osd-branding' in the html, instead of being part of the 'osd-injected-metadata'.
3. On the public side: A new injected branding service is created. Previously the application uses injected metadata service to retrieve the branding information from the core system. Since we have separate branding data out of metadata, now we can just use injected branding service.

Issues Resolved

One possible implementation: Service that components can hook into that assists with the logic
Part of the design spike: opensearch-project#2045

Check List

• New functionality includes testing.
  • All tests pass
    • yarn test:jest
    • yarn test:jest_integration
    • yarn test:ftr
• New functionality has been documented.
• Commits are signed per the DCO using --signoff