feat!: Add snippet u64::trailing_zeros

BREAKING CHANGE: Remove snippet `u64::index_of_last_nonzero_bit`, which
more or less computes the same thing as `trailing_zeros`, but is less
efficient, less general since it fails on input “0”, and uses an
uncommon name.

tasm-lib/benchmarks/tasmlib_arithmetic_u64_trailing_zeros.json

@@ -0,0 +1,24 @@
+[
+  {
+    "name": "tasmlib_arithmetic_u64_trailing_zeros",
+    "benchmark_result": {
+      "clock_cycle_count": 29,
+      "hash_table_height": 42,
+      "u32_table_height": 83,
+      "op_stack_table_height": 17,
+      "ram_table_height": 0
+    },
+    "case": "CommonCase"
+  },
+  {
+    "name": "tasmlib_arithmetic_u64_trailing_zeros",
+    "benchmark_result": {
+      "clock_cycle_count": 30,
+      "hash_table_height": 42,
+      "u32_table_height": 99,
+      "op_stack_table_height": 19,
+      "ram_table_height": 0
+    },
+    "case": "WorstCase"
+  }
+]

tasm-lib/benchmarks/tasmlib_mmr_calculate_new_peaks_from_append.json

@@ -2,9 +2,9 @@
   {
     "name": "tasmlib_mmr_calculate_new_peaks_from_append",
     "benchmark_result": {
-      "clock_cycle_count": 3569,
-      "hash_table_height": 390,
-      "u32_table_height": 197,
+      "clock_cycle_count": 3560,
+      "hash_table_height": 378,
+      "u32_table_height": 131,
       "op_stack_table_height": 3438,
       "ram_table_height": 942
     },
@@ -13,10 +13,10 @@
   {
     "name": "tasmlib_mmr_calculate_new_peaks_from_append",
     "benchmark_result": {
-      "clock_cycle_count": 7035,
-      "hash_table_height": 576,
-      "u32_table_height": 165,
-      "op_stack_table_height": 6806,
+      "clock_cycle_count": 7014,
+      "hash_table_height": 564,
+      "u32_table_height": 130,
+      "op_stack_table_height": 6798,
       "ram_table_height": 1872
     },
     "case": "WorstCase"

tasm-lib/src/arithmetic/u64.rs

@@ -6,7 +6,6 @@ pub mod div_mod;
 pub mod double_pow2;
 pub mod eq;
 pub mod incr;
-pub mod index_of_last_nonzero_bit;
 pub mod leading_zeros;
 pub mod log_2_floor;
 pub mod lt;
@@ -21,6 +20,7 @@ pub mod safe_mul;
 pub mod shift_left;
 pub mod shift_right;
 pub mod sub;
+pub mod trailing_zeros;
 pub mod wrapping_mul;
 pub mod wrapping_sub;
 pub mod xor;