Make DynamicUniformBuffer::push accept an &T instead of T

[SkiFire13]

Objective

• DynamicUniformBuffer::push takes an owned T but only uses a shared reference to it
• This in turn requires users of DynamicUniformBuffer::push to potentially unecessarily clone data

Solution

• Have DynamicUniformBuffer::push take a shared reference to T

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Changelog

• DynamicUniformBuffer::push now takes a &T instead of T

Migration Guide

• Users of DynamicUniformBuffer::push now need to pass references to DynamicUniformBuffer::push (e.g. existing uniforms.push(value) will now become uniforms.push(&value))