Remove array type coercion and fix result location bugs

[andrewrk]

• Implements remove type coercion from array values to references #3768. This is a sweeping breaking change that requires
  many (trivial) edits to Zig source code. Array values no longer
  coerce to slices; however one may use & to obtain a reference to
  an array value, which may then be coerced to a slice.

• Adds IrInstruction::dump, for debugging purposes. It's useful to
  call to inspect the instruction when debugging Zig IR.

• Fixes bugs with result location semantics. See the new behavior test
  cases, and compile error test cases.

• Fixes bugs with @typeInfo not properly resolving const values.

Total bytes used by the compiler (as measured by memory_profiling.cpp) to generate std lib test binary went down by 257 MiB in this branch:

• master: 3.198 GiB
• this branch: 2.947 GiB

[mikdusan]

const std = @import("std");
                
const S0 = struct {
    bar: S1,    
            
    pub const S1 = struct {
        value: u8,  
    };              
                    
    fn init() @This() {
        return S0{ .bar = S1{ .value = 123 } };
    }           
};          
                
var g_foo: S0 = S0.init();

pub fn main() void {
    std.debug.warn("{*}\n", &g_foo);
    g_foo.bar.value = 42;
}

BASELINE

@g_foo = internal unnamed_addr global %S0 { %S1 { i8 123 } }, align 1
...
define internal fastcc void @main.0() unnamed_addr #1 !dbg !13095 {
Entry:
  call fastcc void @std.debug.warn.121(%S0* @g_foo), !dbg !13097
  store i8 42, i8* getelementptr inbounds (%S0, %S0* @g_foo, i32 0, i32 0, i32 0), align 1, !dbg !13099
  ret void, !dbg !13100
}

PR

@g_foo = internal unnamed_addr global %S0 { %S1 { i8 123 } }, align 1
@265 = internal unnamed_addr constant %S0 { %S1 { i8 123 } }, align 1
...
define internal fastcc void @main.0() unnamed_addr #1 !dbg !13095 {
Entry:
  call fastcc void @std.debug.warn.121(%S0* @g_foo), !dbg !13097
  store i8 42, i8* getelementptr inbounds (%S0, %S0* @265, i32 0, i32 0, i32 0), align 1, !dbg !13099
  ret void, !dbg !13100
}

[andrewrk]

This branch is big enough, I'm giving up on solving these test cases in the branch, will attempt again in a new branch after this branch is merged.

    cases.add(
        "function call assigned to incorrect type",
        \\export fn entry() void {
        \\    var arr: [4]f32 = undefined;
        \\    arr = concat();
        \\}
        \\fn concat() [16]f32 {
        \\    return [1]f32{0}**16;
        \\}
    ,
        "tmp.zig:3:17: error: expected type '[4]f32', found '[16]f32'"
    );

    cases.add(
        "generic function call assigned to incorrect type",
        \\pub export fn entry() void {
        \\    var res: []i32 = undefined;
        \\    res = myAlloc(i32);
        \\}
        \\fn myAlloc(comptime arg: type) anyerror!arg{
        \\    unreachable;
        \\}
    ,
        "tmp.zig:3:18: error: expected type '[]i32', found 'anyerror!i32"
    );