Stop using deprecated StringEscapeUtils from commons-lang3

Since version 3.6 of lang3, StringEscapeUtils is deprecated in favor
of the class of the same name in commons-text.

Add a dependency on commons-text, and use StringEscapeUtils from there
instead.

Keep the dependency on commons-lang3 since there is still a dependency
on it (TocFormatter uses StringUtils).

Change-Id: I99448c811672c9ac293e88acbeb99d566a8aebe7

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 21bfa56..7da9440 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -21,6 +21,12 @@
 )
 
 maven_jar(
+    name = "commons_text",
+    artifact = "org.apache.commons:commons-text:1.2",
+    sha1 = "74acdec7237f576c4803fff0c1008ab8a3808b2b",
+)
+
+maven_jar(
     name = "gson",
     artifact = "com.google.code.gson:gson:2.8.2",
     sha1 = "3edcfe49d2c6053a70a2a47e4e1c2f94998a49cf",

java/com/google/gitiles/BUILD

diff --git a/java/com/google/gitiles/BUILD b/java/com/google/gitiles/BUILD
index a4361ed..6e2c554 100644
--- a/java/com/google/gitiles/BUILD
+++ b/java/com/google/gitiles/BUILD
@@ -1,6 +1,7 @@
 DEPS = [
     "//lib:autolink",
     "//lib:commons-lang3",
+    "//lib:commons-text",
     "//lib:gson",
     "//lib:guava",
     "//lib:html-types",

java/com/google/gitiles/HtmlDiffFormatter.java

diff --git a/java/com/google/gitiles/HtmlDiffFormatter.java b/java/com/google/gitiles/HtmlDiffFormatter.java
index 666d5a2..44d2c18 100644
--- a/java/com/google/gitiles/HtmlDiffFormatter.java
+++ b/java/com/google/gitiles/HtmlDiffFormatter.java
@@ -24,7 +24,7 @@
 import java.io.OutputStream;
 import java.util.List;
 import java.util.Map;
-import org.apache.commons.lang3.StringEscapeUtils;
+import org.apache.commons.text.StringEscapeUtils;
 import org.eclipse.jgit.diff.DiffEntry;
 import org.eclipse.jgit.diff.DiffEntry.ChangeType;
 import org.eclipse.jgit.diff.DiffFormatter;

lib/BUILD

diff --git a/lib/BUILD b/lib/BUILD
index 917f5f0..9ee64d5 100644
--- a/lib/BUILD
+++ b/lib/BUILD
@@ -9,6 +9,7 @@
     "autolink",
     "commonmark",
     "commons-lang3",
+    "commons-text",
     "cm-autolink",
     "gfm-strikethrough",
     "gfm-tables",