[Feat]: Provide Sequence as a Backend for APIs

[BLasan]

Provide a separate Endpoint option for REST APIs to define a sequence as its backend. This addresses the following use-cases.

1. Add new Sequence for Production and Sandbox key types.
2. Delete a sequence
3. Download a sequence

UI will now look as follows for the REST APIs.

[CLAassistant]

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[sonarcloud]

Quality Gate passed

Issues
28 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud