[eslint config] [breaking] enable `react/jsx-curly-spacing` rule.
[eslint config] [breaking] enable `react/jsx-curly-spacing` rule.

Fixes #693.
xalexec/javascript,naustudio/javascript,allanfish/javascript,naustudio/javascript,LodoSoftware/javascript-style-guide,airbnb/javascript,webcoding/javascript-style-guide,codelegant/JavaScript,getjll/JavaScript-Style-Guide,nulogy/javascript,codelegant/JavaScript,addshoppers/javascript,LodoSoftware/javascript-style-guide,cloudability/javascript-style-guide,ljharb/javascript,appcom-interactive/javascript,pokelondon/javascript,bl00mber/javascript,practicefusion/javascript,whichdigital/javascript-coding-standards