Enabled bazel build for bssl-compat

[knm3000]

• switched to non-bazel "main" boringssl branch for boringssl submodule to enable copying all files into the bazel sandbox; removed "src" from path (main branch doesn't have "src" folder)
• added "requires-network" tag (cmake needs to download googletest from github)
• replaced realpath() with abspath(); realpath points to local code directory (read-only for bazel build, not possible to generate files), abspath points to sandbox
• added rules_foreign_cc_dependencies parameters (the same as in envoy) to fix cmake build with bazel rules_foreign_cc

For now with these changes bssl-compat part can be build with bazel CC=clang CXX=clang++ bazel build --config=clang @bssl-compat//:bssl-compat, but not the whole repo. When trying to build the full envoy-openssl repo with bazel, there are errors from envoy submodule (handshake-related envoy code), will try to work on it in a separate PR.

[tedjpoole]

Works great. However, I don't understand why the bssl-compat/boringssl submodule was updated.

[knm3000]

@tedjpoole thanks for the review. There are 2 branches of boringssl:

1. Non bazel default master https://github.com/google/boringssl branch
2. master-with-bazel https://github.com/google/boringssl/tree/master-with-bazel
 (currently used in envoy-openssl/bssl-compat) The only difference is that master-with-bazel includes extra bazel BUILD/WORKSPACE files and the source code is located in "src" subdirectory https://github.com/google/boringssl/tree/master-with-bazel/src. 
Everything else is the same: all commits from master are automatically merged into master-with-bazel.

bssl-compat has boringssl as a subdirectory, and cmake without bazel works fine.
 But when building it with bazel, everything is copied into bazel sandbox before the build. When bazel finds WORKSPACE file in a subdirectory, it does not copy such subdirectories into the sandbox (probably it considers them as a separate bazel project). Therefore we get an empty bssl-compat/boringssl subdirectory in the sandbox and cmake (that is called from bazel) fails.

To fix this I changed boringssl submodule from master-with-bazel to master branch (the latest commit remains the same: from Jul 19, 2022 “Mostly Revert 52426 - Drop AVCP support for 3DES”):
 master-with-bazel: https://github.com/google/boringssl/tree/098695591f3a2665fccef83a3732ecfc99acdcdd master: https://github.com/google/boringssl/tree/b95124305ab15c7523d3e21437309fa5dd717ee8