AC-13257::Migrate USPS integration from outdated Web Tools APIs to new RESTful USPS APIs

Author: shashi011

app/code/Magento/Usps/etc/config.xml

@@ -13,6 +13,7 @@
                 <usps_type>USPS_XML</usps_type>
                 <sallowspecific>0</sallowspecific>
                 <allowed_methods>0_FCLE,0_FCL,0_FCP,1,2,3,4,6,7,13,16,17,22,23,25,27,28,33,34,35,36,37,42,43,53,57,61,INT_1,INT_2,INT_4,INT_6,INT_7,INT_8,INT_9,INT_10,INT_11,INT_12,INT_13,INT_14,INT_15,INT_16,INT_20,1058,4058,6058,2058,4096,1096,2096,6096</allowed_methods>
+                <rest_allowed_methods>LIBRARY_MAIL_MACHINABLE_5-DIGIT,MEDIA_MAIL_MACHINABLE_5-DIGIT,USPS_GROUND_ADVANTAGE_MACHINABLE_SINGLE-PIECE,PRIORITY_MAIL_MACHINABLE_SINGLE-PIECE,PRIORITY_MAIL_FLAT_RATE_ENVELOPE,PRIORITY_MAIL_MACHINABLE_MEDIUM_FLAT_RATE_BOX,PRIORITY_MAIL_MACHINABLE_LARGE_FLAT_RATE_BOX,PRIORITY_MAIL_MACHINABLE_SMALL_FLAT_RATE_BOX,PRIORITY_MAIL_PADDED_FLAT_RATE_ENVELOPE,PRIORITY_MAIL_LEGAL_FLAT_RATE_ENVELOPE,PRIORITY_MAIL_EXPRESS_MACHINABLE_SINGLE-PIECE,PRIORITY_MAIL_EXPRESS_FLAT_RATE_ENVELOPE,PRIORITY_MAIL_EXPRESS_LEGAL_FLAT_RATE_ENVELOPE,FIRST-CLASS_PACKAGE_INTERNATIONAL_SERVICE_MACHINABLE_ISC_SINGLE-PIECE,PRIORITY_MAIL_INTERNATIONAL_ISC_SINGLE-PIECE,PRIORITY_MAIL_INTERNATIONAL_ISC_FLAT_RATE_ENVELOPE</rest_allowed_methods>
                 <container>VARIABLE</container>
                 <cutoff_cost />
                 <free_method />