New filter plugin - unicode_normalization (#3359)

* Initial commit

* Adding maintainer in BOTMETA

* Adding changelog fragment

* Updating filter_guide

* Applying initial review suggestions

tests/integration/targets/filter_unicode_normalize/aliases

@@ -0,0 +1,2 @@
+shippable/posix/group2
+skip/python2.6  # filters are controller only, and we no longer support Python 2.6 on the controller

tests/integration/targets/filter_unicode_normalize/tasks/main.yml

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+####################################################################
+# WARNING: These are designed specifically for Ansible tests       #
+# and should not be used as examples of how to write Ansible roles #
+####################################################################
+
+- name: Test 'NFC' normalization
+  assert:
+    that:
+      - u_umlaut != u_umlaut_combining
+      - u_umlaut_combining != (u_umlaut_combining | community.general.unicode_normalize)
+      - u_umlaut == (u_umlaut_combining | community.general.unicode_normalize)
+
+- name: Test 'NFKC' normalization
+  assert:
+    that:
+      - latin_capital_i != roman_numeral_one
+      - latin_capital_i == (roman_numeral_one | community.general.unicode_normalize(form='NFKC'))
+
+- name: Register invalid input type
+  debug:
+    msg: "{{ 1 | community.general.unicode_normalize }}"
+  ignore_errors: true
+  register: invalid_input_type
+
+- name: Assert an invalid input type causes failure
+  assert:
+    that:
+      - invalid_input_type is failed
+
+- name: Register invalid form selection
+  debug:
+    msg: "{{ 'arbitrary text' | community.general.unicode_normalize(form='invalid') }}"
+  ignore_errors: true
+  register: invalid_form_selection
+
+- name: Assert invalid form selection causes failure
+  assert:
+    that:
+      - invalid_form_selection is failed

tests/integration/targets/filter_unicode_normalize/vars/main.yml

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+u_umlaut: "{{ '\u00fc' }}"
+u_umlaut_combining: "{{ 'u' + '\u0308' }}"
+roman_numeral_one: "{{ '\u2160' }}"
+latin_capital_i: "{{ '\u0049' }}"