feat(server): add /settings api for settings shared with frontend

[lykalabrada]

What this PR does / why we need it:

• Added /settings api to return shared config between server and frontend
• Integrated settings api to Fees computation (UI)
• TODO [web]: Get supportedTokens from /settings api to filter out displayed tokens on the bridge form
• TODO [web]: Check other places where fees is used, remove constants
• TODO [api]: Use same supportedTokens to allow/disallow tokens on all API that uses tokens

Which issue(s) does this PR fixes?:

Fixes #638

Additional comments?:

Developer Checklist:

• Read your code changes at least once
• No console errors on web
• Tested on Light mode and Dark mode*
• Your UI implementation visually matched the rendered design*
• Unit tests*
• Added e2e tests*
• Added translations*

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