Shadow map resolution property lacks default value

Shadow map resolution got its own type introduced at some point, but the metadata lacks a default value for it.

<Property name="shdwmapres" formalName="Shadow Resolution" description="Resolution of shadow map (powers of two)" type="ShadowMapResolution" />

This means that:

• in the editor the property shows up with no value in the combo box by default

• the runtime still works but only because it uses the fallback default value hard-coded in C++

The latter is not a real issue, but for the former, and to be consistent with how other properties work when there's a non-zero default value, the MetaData.xml would need the default attribute for shdwmapres as well:

default="9"