Move useTemplate and useSimplifiedLogicalExpression to style group

[MichaReiser]

Question

To move the following rules to the stylistic lint group:

• useTemplate: Recommends using template literals over string concatenation. In my view, this is more a stylistic preference than preventing bugs (both variants can become difficult to read when they contain a lot or specially complicated placeholders).
• useSimplifiedExpression: Helps to simplify logical expression. I can see the point how complex expression may increase the likeliness of bugs but sometimes comes down to how someone prefers to group logical expressions (arguably, it may then be recommended to create temporary variables).

Recommendation

Rules to be in stylistic group

[ematipico]

We could follow clippy lead, and move useSimplifiedExpression under a new group called complexity:

code that does something simple but in a complex way

If you check their Complexity group here https://rust-lang.github.io/rust-clippy/master/index.html (you need to select the filter), there's a bunch of rules around binary expressions.

[MichaReiser]

I like that!

[ematipico]

This proposal is implemented in #3471