bazel: Add initial config for binary distribution (see #3757)

Add support for building the CEF binary distribution using Bazel
and the default platform toolchain. Tested to work for Windows
x64, MacOS ARM64 and x64 (cross-compile from ARM64), and
Linux x64. Windows x86 (cross-compile from x64) is known to
be broken, see https://github.com/bazelbuild/bazel/issues/22164.

Includes minor changes to tests directory structure to meet
Bazel build requirements.

bazel/linux/exe_helpers.bzl

@@ -0,0 +1,58 @@
+# Copyright (c) 2024 The Chromium Embedded Framework Authors. All rights
+# reserved. Use of this source code is governed by a BSD-style license that
+# can be found in the LICENSE file.
+
+load("//bazel:copy_filegroups.bzl", "copy_filegroups")
+load("//bazel/linux:fix_rpath.bzl", "fix_rpath")
+load("//bazel/linux:variables.bzl",
+     "COMMON_LINKOPTS",
+     "COMMON_COPTS", "COMMON_COPTS_RELEASE", "COMMON_COPTS_DEBUG")
+load("@rules_cc//cc:defs.bzl", "cc_binary")
+
+def declare_exe(name, srcs=[], deps=[], linkopts=[], copts=[], defines=[], data=[]):
+    # Copy SOs and resources into the current project.
+    copy_target = "{}_sos_and_resources".format(name)
+    copy_filegroups(
+        name = copy_target,
+        filegroups = [
+            "//:sos",
+            "//:resources",
+        ],
+        remove_prefixes = [
+            "Debug",
+            "Release",
+            "Resources",
+        ],
+    )
+
+    # Executable target.
+    binary_target = "{}_incorrect_rpath".format(name)
+    cc_binary(
+        name = binary_target,
+        srcs = srcs,
+        deps = [
+            "//:cef_wrapper",
+            "//:cef",
+            "//:cef_sandbox",
+        ] + deps,
+        linkopts = COMMON_LINKOPTS + linkopts,
+        copts = select({
+            "//:linux_dbg": COMMON_COPTS_DEBUG,
+            "//conditions:default": COMMON_COPTS_RELEASE,
+        }) + COMMON_COPTS + copts,
+        defines = defines,
+        data = [
+            ":{}".format(copy_target),
+        ] + data,
+        target_compatible_with = ["@platforms//os:linux"],
+    )
+
+    # Set rpath to $ORIGIN so that libraries can be loaded from next to the
+    # executable.
+    fix_rpath(
+        name = "{}_fixed_rpath".format(name),
+        src = ":{}".format(binary_target),
+        out = name,
+        target_compatible_with = ["@platforms//os:linux"],
+    )
+