intel/fs: move final send lowering up into the IR

What does this MR do and why?

Because we do emit the final send message form in code generation, a
lot of emissions look like this :

add(8) vgrf0, u0, 0x100
mov(1) a0.1, vgrf0 # emitted by the generator
send(8) ..., a0.1

By moving address register manipulation in the IR, we can get this
down to :

add(1) a0.1, u0, 0x100
send(8) ..., a0.1

This reduce register pressure around some send messages by 1 vgrf.

All lost shaders in the below results are fragment SIMD32, due to the throughput estimator. If turned off, we loose no SIMD32 shaders with this change.

DG2 results :

 PERCENTAGE DELTAS Shaders   Instrs  Subgroup size Cycle count Spill count Fill count Max live registers Max dispatch width
 cyberpunk_2077    10587     -0.43%      -0.01%       +2.89%      -5.88%     -6.90%         -0.22%             -0.30%
 ----------------------------------------------------------------------------------------------------------------------------
 All affected      10252     -0.44%      -0.01%       +2.89%      -5.88%     -6.90%         -0.22%             -0.31%
 ----------------------------------------------------------------------------------------------------------------------------
 Total             10587     -0.43%      -0.01%       +2.89%      -5.88%     -6.90%         -0.22%             -0.30%

 (gaining 32, loosing 49)

 PERCENTAGE DELTAS Shaders Cycle count Max live registers Max dispatch width
 dota2_g2          1498       +0.22%         -0.01%             -0.76%
 -----------------------------------------------------------------------------
 All affected      192        +2.58%         -0.12%             -7.06%
 -----------------------------------------------------------------------------
 Total             1498       +0.22%         -0.01%             -0.76%

 (loosing 7)

 PERCENTAGE DELTAS Shaders   Instrs  Cycle count Max live registers Max dispatch width
 strange_brigade   4108      -1.08%     +1.69%         -0.15%             -0.10%
 ---------------------------------------------------------------------------------------
 All affected      3649      -1.10%     +1.71%         -0.16%             -0.11%
 ---------------------------------------------------------------------------------------
 Total             4108      -1.08%     +1.69%         -0.15%             -0.10%

 (loosing 2)

TGL results :

 PERCENTAGE DELTAS Shaders   Instrs  Subgroup size Cycle count Spill count Fill count Max live registers Max dispatch width
 cyberpunk_2077    10373     -0.00%      +0.01%       +0.38%      -0.33%     -0.15%         -0.07%             +0.04%
 ----------------------------------------------------------------------------------------------------------------------------
 All affected      7087      -0.00%      +0.01%       +0.49%      -0.33%     -0.15%         -0.09%             +0.06%
 ----------------------------------------------------------------------------------------------------------------------------
 Total             10373     -0.00%      +0.01%       +0.38%      -0.33%     -0.15%         -0.07%             +0.04%

 (gaining 4, loosing 3)

 PERCENTAGE DELTAS Shaders Cycle count Max live registers Max dispatch width
 dota2_g2          1517       +0.34%         -0.77%             -6.13%
 -----------------------------------------------------------------------------
 All affected      234        +3.12%         -6.11%             -27.23%
 -----------------------------------------------------------------------------
 Total             1517       +0.34%         -0.77%             -6.13%

 (loosing 52)

 PERCENTAGE DELTAS Shaders   Instrs  Cycle count Max live registers Max dispatch width
 strange_brigade   1951      +0.00%     +1.02%         -0.55%             -0.30%
 ---------------------------------------------------------------------------------------
 All affected      988       +0.01%     +1.64%         -0.91%             -0.60%
 ---------------------------------------------------------------------------------------
 Total             1951      +0.00%     +1.02%         -0.55%             -0.30%

 (loosing 3)

 PERCENTAGE DELTAS Shaders   Instrs  Cycle count Max dispatch width
 witcher_3_dxvk_g2 1034      -0.00%     -0.00%         -0.18%
 --------------------------------------------------------------------
 All affected      4         -0.40%     -1.44%         -33.33%
 --------------------------------------------------------------------
 Total             1034      -0.00%     -0.00%         -0.18%

 (loosing 1)

Includes !28188 (merged)

Will add some shader-db stats shortly.