Add `GetPlatformInfo` action

[nikkita1267]

This pull request implements the GetPlatformInfo action, closes #6.

I left libc_ver and install_date fields blank because function Uname.FromCurrentSystem (link) doesn't fill them. I also add libc crate which provides uname system call.

All fields, except libc_ver and install_date, are currently filled for Linux.

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[nikkita1267]

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