Update indent rule with sane defaults for JSX

As discussed in https://github.com/eslint/eslint/pull/7618, now that the indent rewrite has landed, we should enhance it with sane defaults for JSX, allowing for users who prefer to use a custom rule like eslint-plugin-react to do so with an ignoreJSX option.

Note: It already currently checks JSX. The proposal here is to update the rule to make it allow for common JSX styles and fix any bugs we see. Ideally, people won’t have to use the ignoreJSX option. Actually, maybe we should hold off on that option and wait and see if anyone asks for it? It would be nice if everyone could just use the indent rule, since we support JSX out of the box!

So far, the following enhancements have been discussed:

• Allow for props to be inline or multiline indented one level
• Closing tags should be inline or indented at same level as opening tag
• The first level of indentation for JS expressions inside JSXExpressionContainer nodes needs to be calculated correctly

[kaicataldo]

Defaulting to line-aligned seems like the best course of action to me, then!

[not-an-aardvark]

@soda0289 That would be determined by the VariableDeclarator option. Both of the examples would be allowed depending on whether the VariableDeclarator config was 1 or 0, respectively.

Basically, if you squint a bit and pretend that the JSXElement is an object literal and the attributes are properties, the same thing will be allowed for the element as for the corresponding object literal.