test: regex_ testcases (#54972)

Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>

test/integration/targets/filters/files/foo.txt

@@ -56,6 +56,7 @@ TODO: realpath follows symlinks.  There isn't a test for this just now.
 
 TODO: add tests for set theory operations like union
 
-TODO: add tests for regex, match, and search
+regex_replace = bar
-
+regex_search = 0001
-
+regex_findall = "['car', 'tar', 'bar']"
+regex_escape = \^f\.\*o\(\.\*\)\$

test/integration/targets/filters/templates/foo.j2

@@ -50,6 +50,7 @@ TODO: realpath follows symlinks.  There isn't a test for this just now.
 
 TODO: add tests for set theory operations like union
 
-TODO: add tests for regex, match, and search
+regex_replace = {{ 'foo' | regex_replace('^foo', 'bar') }}
-
+regex_search = {{ 'test_value_0001' | regex_search('([0-9]+)$')}}
-
+regex_findall = "{{ 'car\ntar\nfoo\nbar\n' | regex_findall('^.ar$', multiline=True) }}"
+regex_escape = {{ '^f.*o(.*)$' | regex_escape() }}