Enable no-use-before-declare in source code

[reduckted]

The no-use-before-declare was temporarily disabled as part of #567. It needs to be re-enabled.

[reduckted]

Most of the lint errors caused by this rule would be fixed once #586 is fixed, because the majority are caused by the RuleWalker class being declared after the Rule class.

[JoshuaKGoldberg]

Hey, sorry to shut this down, but I think we can skip having the rule enabled. Per the docs:

This rule is primarily useful when using the var keyword since the compiler will automatically detect if a block-scoped let and const variable is used before declaration. Since most modern TypeScript doesn’t use var, this rule is generally discouraged and is kept around for legacy purposes. It is slow to compute, is not enabled in the built-in configuration presets, and should not be used to inform TSLint design decisions.

Thoughts?

[reduckted]

Thoughts?

Sounds good to me. All of the errors seemed to be around classes being "used" before they were defined (which wasn't technically the case), and by the sounds of it, the rule is targeted more at variables than classes.