Build failing in MSVC 2017

[SlugFiller]

Tested versions

Introduced in #83452

System information

Windows, MSVC 2017

Issue description

This union is causing an issue:

	union RenderPassClearValue {
		Color color = {};
		struct {
			float depth;
			uint32_t stencil;
		};
	};

Since Color does not have a default constructor, it results in the following message:

servers/rendering/rendering_device_driver.h(538): note: 'RenderingDeviceDriver::RenderPassClearValue::RenderPassClearValue(void)': function was implicitly deleted because 'RenderingDeviceDriver::RenderPassClearValue' has a variant data member 'RenderingDeviceDriver::RenderPassClearValue::color' with a non-trivial default constructor

Steps to reproduce

1. Install MSVC 2017
2. Clone master
3. Build using SCons

Minimal reproduction project (MRP)

N/A

[YuriSizov]

cc @RandomShaper