[Feature] support shm mapping and register

[DwyaneShi]

Pull Request Description

This PR is to support exchanging shm info between server and client.

On server side:

• get shm fd
• register with cuda api (ensure all pages are pinned down)
• send pid and shm fd to new connections

On client side:

• get pid and shm fd after handshake
• mmap shm
• register with cuda api (to make it accessible by gpus)

Related Issues

Resolves: #[Insert issue number(s)]

Important: Before submitting, please complete the description above and review the checklist below.

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• PR title includes appropriate prefix(es)
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[yapple]

Compile failed with PRISKV_USE_CUDA=0

/usr/bin/ld: /tmp/ccfG8uqG.o: undefined reference to symbol 'dlsym@@GLIBC_2.2.5'
/usr/bin/ld: //lib/x86_64-linux-gnu/libdl.so.2: error adding symbols: DSO missing from command line

[DwyaneShi]

Compile failed with PRISKV_USE_CUDA=0

/usr/bin/ld: /tmp/ccfG8uqG.o: undefined reference to symbol 'dlsym@@GLIBC_2.2.5'
/usr/bin/ld: //lib/x86_64-linux-gnu/libdl.so.2: error adding symbols: DSO missing from command line

fixed