ICU-20243 Enable the Exhaustive Tests in the CI builds.

Using a separate YML file for the Exhaustive Tests configuration so that the Azure Pipelines build can be run separately.
diff --git a/.ci-builds/.azure-exhaustive-tests.yml b/.ci-builds/.azure-exhaustive-tests.yml
new file mode 100644
index 0000000..9b77700
--- /dev/null
+++ b/.ci-builds/.azure-exhaustive-tests.yml
@@ -0,0 +1,53 @@
+# Azure Pipelines configuration for Exhaustive Tests for ICU.
+# 
+# Note: The exhaustive test configuration is in a separate file
+# so that it can be run independently from the regular builds.
+#
+
+resources:
+  - repo: self
+    lfs: true
+    fetchDepth: 1
+
+jobs:
+#-------------------------------------------------------------------------
+# Note: The exhaustive tests for J take longer than the C tests. They 
+# take roughly 85 min to complete on the Azure VMs.
+- job: ICU4J_OpenJDK_Ubuntu_1604
+  displayName: 'J: Linux OpenJDK (Ubuntu 16.04)'
+  timeoutInMinutes: 100
+  pool:
+    vmImage: 'Ubuntu 16.04'
+    demands: ant
+  steps:
+    - script: |
+        echo "Building ICU4J" && cd icu4j && ant init && ant exhaustiveCheck
+      displayName: 'Build and Exhaustive Tests'
+      env:
+        BUILD: ICU4J
+    - script: |
+        cat `find out/junit-results -name "*.txt" -exec grep -l FAILED {} \;`
+      condition: failed() # only run if the build fails.
+      displayName: 'List failures (if any)'
+#-------------------------------------------------------------------------
+# Note: The exhaustive tests take roughly 65 mins to complete on the
+# Azure VMs.
+- job: ICU4C_Clang_Exhaustive_Ubuntu_1604
+  displayName: 'C: Linux Clang Exhaustive Tests (Ubuntu 16.04)'
+  timeoutInMinutes: 80
+  pool:
+    vmImage: 'Ubuntu 16.04'
+  steps:
+    - script: |
+        cd icu4c/source && ./runConfigureICU Linux && make -j2
+      displayName: 'Build'
+    - script: |
+        cd icu4c/source && make check
+      displayName: 'Exhaustive Tests'
+      env:
+        INTLTEST_OPTS: '-e'
+        CINTLTEST_OPTS: '-e'
+        CC: clang
+        CXX: clang++
+#-------------------------------------------------------------------------
+