Enable no-useless-escape lint rule

Summary: See https://eslint.org/docs/rules/no-useless-escape. Useless escapes can reflect a mismatch between the intended and actual effect of a backslash in a literal.

Reviewed By: rubennorte

Differential Revision: D17876784

fbshipit-source-id: 7641b1f2227b92e1e91469adc0d0d990a64109cf

packages/eslint-config-react-native-community/index.js

@@ -179,6 +179,7 @@ module.exports = {
     'no-self-compare': 1, // disallow comparisons where both sides are exactly the same (off by default)
     'no-sequences': 1, // disallow use of comma operator
     'no-unused-expressions': 0, // disallow usage of expressions in statement position
+    'no-useless-escape': 1, // disallow escapes that don't have any effect in literals
     'no-void': 1, // disallow use of void operator (off by default)
     'no-warning-comments': 0, // disallow usage of configurable warning terms in comments": 1,                        // e.g. TODO or FIXME (off by default)
     'no-with': 1, // disallow use of the with statement