Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>

- Introduce elv used for the communication with ra-tls-server
- ra-tls-server now is moved out from wolfssl-examples
- Remove wolfssl-examples in build process
Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>

Signed-off-by: NYilin Li <YiLin.Li@linux.alibaba.com>

1. Given the signature file of an Enclave, runectl gen-token command can generate the corresponding token file from Intel aesmd service.
2. runectl attest command can allow users to challenge the enclave with the help of Intel Attestation Service through remote attestation
requests. runectl command will open soon.
Signed-off-by: NYilin Li <YiLin.Li@linux.alibaba.com>
Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>