NoMongo : Implement Membership Mutations

[khushipatil1523]

Is your feature request related to a problem? Please describe.
Currently, there are no GraphQL mutations to handle membership requests efficiently. Users cannot send a request to join a private organization, join a public organization instantly, or cancel a pending request. This limits the flexibility of user onboarding and membership management within the system.

Description
In this PR, I will be adding the following GraphQL mutations for managing organization memberships:

sendMembershipRequest(organizationId: ID!): Boolean – Allows users to request membership in a private organization.
joinPublicOrganization(organizationId: ID!): Boolean – Enables users to instantly join a public organization.
cancelMembershipRequest(organizationId: ID!): Boolean – Lets users cancel a pending membership request.
This implementation will follow existing GraphQL patterns, ensuring:

1. Consistency with the current schema and resolver structure.
2. Proper error handling and input validation.

Approach to be followed (optional)
Same as used for other mutations, adhering to the current schema and resolver structure to maintain consistency. 🚀

[khushipatil1523]

@palisadoes can i work on this?

[github-actions]

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