spread condition for input element

[tanhauhau]

Fixes #4418

When updating input.value, we check whether input.value === value before setting it:

p(ctx, [dirty]) {
	if (dirty & /*value*/ 1 && input.value !== /*value*/ ctx[0]) {
		input.value = /*value*/ ctx[0];
	}
},

however we didnt check this when using spread:

p(ctx, [dirty]) {
	set_attributes(input, input_data = get_spread_update(input_levels, [
		{}, 
		dirty & /*value*/ 1 && { value: /*value*/ ctx[0] }
	]));
},

this MR tries to fix this

p(ctx, [dirty]) {
	set_attributes(input, input_data = get_spread_update(input_levels, [
		{}, 
-		dirty & /*value*/ 1 && { value: /*value*/ ctx[0] }
+		dirty & /*value*/ 1 && input.value !== /*value*/ ctx[0] && { value: /*value*/ ctx[0] }
	]));
},

I did some moving code around, so i can extract the logic from Attribute#render that handles the special case for input.value, input.src, should_cache, etc, still figuring out what's the best way to refactor them, suggestions welcome.

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[Conduitry]

@tanhauhau Can you take a look at the conflict here please? In particular, we need to make sure the changes in #5054 are reflected in the code that this PR moves to another location.