pw_tls_client: Add crlset component

Add support for CRLSet, including a build target, API header and docs.

Bug: 396
Change-Id: I633219f190cae858fa8e77773a7eef971da99cbb
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/48540
Commit-Queue: Yecheng Zhao <zyecheng@google.com>
Reviewed-by: Ali Zhang <alizhang@google.com>
diff --git a/pw_tls_client/BUILD b/pw_tls_client/BUILD
index cc8f82d..d688cdc 100644
--- a/pw_tls_client/BUILD
+++ b/pw_tls_client/BUILD
@@ -69,3 +69,12 @@
         "build_time.cc",
     ],
 )
+
+pw_cc_library(
+    name = "crlset",
+    hdrs = ["public/pw_tls_client/crlset.h"],
+    includes = ["public"],
+    deps = [
+        "//pw_bytes",
+    ],
+)