This change is a shift in how conversion sequences and overload scoring
is handled to disambiguate a few cases that DXC handles today through
simpler rules.

The main cases relate to scoring conversion sequences with dimension
adjustment conversions. With this change an implicit conversion sequence
is now defined as:

* Value conversion (lvalue to rvalue or array decay)
* Data conversion (int/float/bool/struct promotion or conversion)
* Dimension conversion (splat or truncate)
* CV qualifier conversion (add const)

Conversion sequences are still assigned the rank of their "highest"
conversion following the same chart as before where the ranks are:

* Exact Match
* Extension
* Promotion
* Conversion
* Truncation

There is an added rule that if two conversion sequences are both of rank
*Promotion* or "Conversion" and one contains an *Extension* but the
other does not, the conversion without the *Extension* is the better
conversion sequence.

Given these rules:

ICS(float -> double) > ICS(float -> double3)
ICS(float -> double3) > ICS(float -> half)
ICS(float -> double2) == ICS(float -> dobule3)
ICS(float -> half) > ICS(float -> half3)
ICS(float4 -> double3) > ICS(float4 -> half3)
ICS(float4 -> double4) > ICS(float4 -> float2)
ICS(float4 -> half4) > ICS(float4 -> float2)

This updates the ordering of conversion ranks and disambiguation rule to handle a few more cases:

ICS(float -> double) > ICS(float -> float3)
ICS(float -> float3) > ICS(float -> double3)
ICS(float -> double4) > ICS(float -> half4)
ICS(float -> double4) != ICS(float -> double3)
ICS(double -> float4) != ICS(double -> float3)
ICS(double -> float4) != ICS(double -> half3)

ICS(float4 -> float3) > ICS(float4 -> double3)
ICS(float4 -> float3) > ICS(float4 -> half3)
ICS(float4 -> double3) > ICS(float4 -> half3)
ICS(double4 -> float3) != ICS(double4 ->half3)
ICS(half4 -> float3) != ICS(half4 ->double3)

It is no longer relevant