Make creating a CcToolchainConfigInfo from Skylark possible

Work towards issue #5380.

//tools/cpp/cc_toolchain_config_lib.bzl contains all the necessary functionality for
one to be able to create a CcToolchainConfigInfo provider from Skylark. CcToolchainConfigInfo currently encapsulates the info read from the CROSSTOOL file. We are moving away from using the CROSSTOOL files, in the future we will reroute the logic
through an attribute of cc_toolchain that will point to a Skylark rule.
A CcToolchainConfigInfo provider can be created with the cc_common.create_cc_toolchain_config_info()
method.

e.g:

crosstool_rule = rule{
    implementation = _impl,
    provides = [CcToolchainConfigInfo],
)

def _impl(ctx):
    feature1 = feature(
        name = "feature_one",
        flag_sets = [
            flag_set(actions = ["action1"]),
            flag_set(
                actions = ["action1"],
                flag_groups = [
                    flag_group(
                        flags = ["flag1"],
                    ),
                    flag_group(
                        flag_groups = [
                            flag_group(
                                flags = ["flag1"],
                            ),
                        ],
                        expand_if_equal = variable_with_value(
                            name = "variable1",
                            value = "value",
                        ),
                    ),
                ],
                expand_if_all_available = ["sysroot"],
            ),
        ],
    )
    action_config1 = action_config(action_name = "action_one", enabled = True)
    action_config2 = action_config(
        action_name = "action_two",
        enabled = True,
        tools = [tool(path = "/a/b/c")],
    )
    artifact_name_pattern1 = artifact_name_pattern(
        category_name = "static_library",
        prefix = "prefix",
        extension = ".a",
    )
    cc_target_os = "os"

    return  cc_common.create_cc_toolchain_config_info(
        features = [feature1],
        action_configs = [action_config1, action_config2],
        artifact_name_patterns = [artifact_name_pattern1],
        cc_target_os = cc_target_os,
        make_variables = [make_variable(name = "v1", value = "val")],
    )

RELNOTES: None.
PiperOrigin-RevId: 209648136

src/main/java/com/google/devtools/build/lib/bazel/rules/CcRules.java

@@ -29,6 +29,7 @@
 import com.google.devtools.build.lib.rules.cpp.CcLibcTopAlias;
 import com.google.devtools.build.lib.rules.cpp.CcLinkingInfo;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainAliasRule;
+import com.google.devtools.build.lib.rules.cpp.CcToolchainConfigInfo;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainRule;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainSuiteRule;
 import com.google.devtools.build.lib.rules.cpp.CppBuildInfo;
@@ -80,6 +81,7 @@ public void init(ConfiguredRuleClassProvider.Builder builder) {
     builder.addSkylarkBootstrap(new CcBootstrap(new BazelCcModule()));
     builder.addSkylarkAccessibleTopLevels("CcCompilationInfo", CcCompilationInfo.PROVIDER);
     builder.addSkylarkAccessibleTopLevels("CcLinkingInfo", CcLinkingInfo.PROVIDER);
+    builder.addSkylarkAccessibleTopLevels("CcToolchainConfigInfo", CcToolchainConfigInfo.PROVIDER);
   }
 
   @Override

src/main/java/com/google/devtools/build/lib/rules/cpp/BUILD

@@ -40,6 +40,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/rules/apple",
         "//src/main/java/com/google/devtools/build/lib/shell",
         "//src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec",
+        "//src/main/java/com/google/devtools/build/lib/skylarkbuildapi",
         "//src/main/java/com/google/devtools/build/lib/skylarkbuildapi/cpp",
         "//src/main/java/com/google/devtools/build/lib/vfs",
         "//src/main/java/com/google/devtools/build/skyframe",