[REF] web: convert FieldBoolean to owl

This commit does 4 things:
- adds a file for deprecated legacy fields.
- moves legacy FieldBoolean into this file.
- converts FieldBoolean to owl component.
- adds a new xml file for component fields' templates.

task id: 2193996

addons/web/static/src/xml/fields.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<templates id="template" xml:space="preserve">
+
+    <t t-name="web.FieldBoolean" owl="1">
+        <CustomCheckbox disabled="mode === 'readonly'" value="value"
+            class="o_field_boolean" t-on-change="_onChange"/>
+    </t>
+
+</templates>