Add bazel support to embed files into binaries directly.

[ccontavalli-j]

This is step 2/N to have better toolchains, and embed eBPF code into binaries.

The .bzl rule imported allows to link files directly into binaries.

Example:

• You have a "trie_match.o" containing ebpf code.
• You use cc_embed(name = "trie_match", data = [":trie_match.o"])
• From your .cc file, you can now include "trie_match.h", and use std::string_view trie_match_o to access the raw bytes contained in the file.

This should work with separate targets as well, where :trie_match is on its own generated by other rules.