udpa: UDPA URL encoding/decoding utils. (#11805)

This patch introduces support for encoding/decoding
udpa::core::v1::ResourceLocator, in addition to the existing support for
udpa::core::v1::ResourceName. Some refactoring and attention to the
URI/URN/URL distinction (as per RFC3986) is introduced.

Part of #11264

Risk level: Low (not used)
Testing: Additional unit tests for URLs added.

Signed-off-by: Harvey Tuch <htuch@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 76525d8d9e3fb8b0b979f8ada5e152a3ddf14019

bazel/repository_locations.bzl

@@ -13,8 +13,8 @@ GOOGLEAPIS_SHA = "a45019af4d3290f02eaeb1ce10990166978c807cb33a9692141a076ba46d14
 PROMETHEUS_GIT_SHA = "99fa1f4be8e564e8a6b613da7fa6f46c9edafc6c"  # Nov 17, 2017
 PROMETHEUS_SHA = "783bdaf8ee0464b35ec0c8704871e1e72afa0005c3f3587f65d9d6694bf3911b"
 
-UDPA_GIT_SHA = "ca580c4fcf87b178547c2e9e41a2481b0008efe9"  # June 24, 2020
-UDPA_SHA256 = "a1dc305cd56f1dd393fec8ec6b19f4f7d76af9740c7746e9377c8dd480f77e70"
+UDPA_GIT_SHA = "efcf912fb35470672231c7b7bef620f3d17f655a"  # June 29, 2020
+UDPA_SHA256 = "0f8179fbe3d27b89a4c34b2fbd55832f3b27b6810ea9b03b36d18da2629cc871"
 
 ZIPKINAPI_RELEASE = "0.2.2"  # Aug 23, 2019
 ZIPKINAPI_SHA256 = "688c4fe170821dd589f36ec45aaadc03a618a40283bc1f97da8fa11686fc816b"