feat: add user-blocks operations by identifier

[mhsu-auth0]

Proposed Changes

• Add support for https://auth0.com/docs/api/management/v2#!/User_Blocks/get_user_blocks
• Add support for https://auth0.com/docs/api/management/v2#!/User_Blocks/delete_user_blocks

Acceptance Test Output

$ go test ./... -v -run TestUser

Community Note

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[yvovandoorn]

Thank you for your contribution @mhsu-auth0! Looks good.