Fix GetPropFloatArray indexing on Vector members

[samisalreadytaken]

I remember testing this feature, but apparently at some point in development it broke and I didn't check again.

Test with

assert( SERVER_DLL );

local function Set( idx )
{
	NetProps.SetPropFloatArray( player, "m_vecMissPositions", 0.1 + idx, 0 + idx * 3 );
	NetProps.SetPropFloatArray( player, "m_vecMissPositions", 0.2 + idx, 1 + idx * 3 );
	NetProps.SetPropFloatArray( player, "m_vecMissPositions", 0.3 + idx, 2 + idx * 3 );
}

local function Get( idx )
{
	assert( NetProps.GetPropFloatArray( player, "m_vecMissPositions", 0 + idx * 3 ) == 0.1 + idx );
	assert( NetProps.GetPropFloatArray( player, "m_vecMissPositions", 1 + idx * 3 ) == 0.2 + idx );
	assert( NetProps.GetPropFloatArray( player, "m_vecMissPositions", 2 + idx * 3 ) == 0.3 + idx );
}

local size = NetProps.GetPropArraySize( player, "m_vecMissPositions" );

for ( local i = 0; i < size; ++i )
{
	Set( i );
	Get( i );
}

Set( -1 );
Set( size );

assert( NetProps.GetPropFloatArray( player, "m_vecMissPositions", -1 ) == -1.0 );
assert( NetProps.GetPropFloatArray( player, "m_vecMissPositions", 0 + size * 3 ) == -1.0 );

NetProps.SetPropFloatArray( player, "m_Local.m_vecPunchAngle", 0.25, 0 );
NetProps.SetPropFloatArray( player, "m_Local.m_vecPunchAngle", 0.50, 1 );
NetProps.SetPropFloatArray( player, "m_Local.m_vecPunchAngle", 0.75, 2 );
assert( NetProps.GetPropFloatArray( player, "m_Local.m_vecPunchAngle", 0 ) == 0.25 );
assert( NetProps.GetPropFloatArray( player, "m_Local.m_vecPunchAngle", 1 ) == 0.50 );
assert( NetProps.GetPropFloatArray( player, "m_Local.m_vecPunchAngle", 2 ) == 0.75 );

print("done\n");

NetProps.Dump( player, "!test.log" );
/*
m_vecMissPositions <vec3 array> #16
[
	[0.100000 0.200000 0.300000]
	[1.100000 1.200000 1.300000]
	[2.100000 2.200000 2.300000]
	[3.100000 3.200000 3.300000]
	[4.100000 4.200000 4.300000]
	[5.100000 5.200000 5.300000]
	[6.100000 6.200000 6.300000]
	[7.100000 7.200000 7.300000]
	[8.100000 8.200000 8.300000]
	[9.100000 9.200000 9.300000]
	[10.100000 10.200000 10.300000]
	[11.100000 11.200000 11.300000]
	[12.100000 12.200000 12.300000]
	[13.100000 13.200000 13.300000]
	[14.100000 14.200000 14.300000]
	[15.100000 15.200000 15.300000]
]
*/

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• My PR follows all guidelines in the CONTRIBUTING.md file
• My PR targets a develop branch OR targets another branch with a specific goal in mind