add new API to create token and accept issuer as explicit param
add new API to create token and accept issuer as explicit param

MienDev/IdentityServer4,MienDev/IdentityServer4,chrisowhite/IdentityServer4,IdentityServer/IdentityServer4,IdentityServer/IdentityServer4,IdentityServer/IdentityServer4,IdentityServer/IdentityServer4,chrisowhite/IdentityServer4,chrisowhite/IdentityServer4,MienDev/IdentityServer4,MienDev/IdentityServer4