Proposal: Rust-like if, while and for syntax

[ghost]

In my opinion, the rust-like syntax

if condition { expr }

where the {} are forced, but the () around the condition can be omitted is easier to read and write than the c-like

if (condition) expr

syntax.
I think this change would benefit zig because IMHO omitting the {} almost always makes the code more unreadable, the structure given by the {} helps really to see where the expression ends. Furthermore, when the {} are forced, the () doesn't really help here, since the condition is already well separated by the if and the {.

[emekoi]

see #4294 and #1659.