fix(preset): class-properties, private-methods and private-property-in-object must have the same "loose" configuration

[osdevisnot]

This MR fixes below warnings:

Though the "loose" option was set to "false" in your @babel/preset-env config, it will not be used for @babel/plugin-proposal-private-property-in-object since the "loose" mode option was set to "true" for @babel/plugin-proposal-class-properties.
The "loose" option must be the same for @babel/plugin-proposal-class-properties, @babel/plugin-proposal-private-methods and @babel/plugin-proposal-private-property-in-object (when they are enabled): you can silence this warning by explicitly adding
	["@babel/plugin-proposal-private-property-in-object", { "loose": true }]
to the "plugins" section of your Babel config.

Without this fix, all users of babel-plugin-zillow will need to include this configuration in their local babel config.

NB: This MR superseeds and closes #11