Maps should allow storing more primitive types without wrapping them in structs

[anton-trunov]

For instance, map<Int, Bool> is not directly supported and instead, the user can either emulate booleans with integers and use map<Int, Int> or wrap a boolean into a struct like so:

struct BoolValue {
    value: Bool;
}

boolArray: map<Int, BoolValue>;

(the example above is due to @hitasp: https://t.me/tactlang/11016)

[anton-trunov]

We should also allow strings and coins as map value type (these are allowed when wrapped in a structure anyways).

[Gusarich]

actually Bool is already supported. but Slice, String, and Builder are not, so I'll work on their support.