Add new TDCALL functions to support TD partitioning

[vijaydhanraj]

Fixes: https://github.com/confidential-containers/td-shim/issues/707

Added the following TDCALL support as part of this PR.

• Wrapper to tdcall_accept_page to accept a memory range (for both normal 4K as well as 2M large pages).
• Add tdcall_vm_read/write to access TD-scope meta field of a TD.
• Add tdcall_vp_read/write is to access vCPU-scope meta field of a TD.
• Add tdcall_vp_invept/invvpid to provide SEPT flushing support.
• Add tdcall_vp_enter support.
• Add tdcall to support memory attribute write.