[MLIR][TBLGen] Added compound assignment operator for any BitEnum (#160840)

## Details:
- Added missing compound assignment operators `|=`, `&=`, `^=` to
`mlir-tblgen`
- Replaced the arithmetic operators with added assignment operators for
`BitEnum` in the transformations
- Updated related documentation


## Tickets:
- Closes llvm/llvm-project#158098

Author: a-sidorova

mlir/tools/mlir-tblgen/EnumsGen.cpp

@@ -364,6 +364,9 @@ getAllBitsUnsetCase(llvm::ArrayRef<EnumCase> cases) {
 // inline constexpr <enum-type> operator|(<enum-type> a, <enum-type> b);
 // inline constexpr <enum-type> operator&(<enum-type> a, <enum-type> b);
 // inline constexpr <enum-type> operator^(<enum-type> a, <enum-type> b);
+// inline constexpr <enum-type> &operator|=(<enum-type> &a, <enum-type> b);
+// inline constexpr <enum-type> &operator&=(<enum-type> &a, <enum-type> b);
+// inline constexpr <enum-type> &operator^=(<enum-type> &a, <enum-type> b);
 // inline constexpr <enum-type> operator~(<enum-type> bits);
 // inline constexpr bool bitEnumContainsAll(<enum-type> bits, <enum-type> bit);
 // inline constexpr bool bitEnumContainsAny(<enum-type> bits, <enum-type> bit);
@@ -385,6 +388,15 @@ inline constexpr {0} operator&({0} a, {0} b) {{
 inline constexpr {0} operator^({0} a, {0} b) {{
   return static_cast<{0}>(static_cast<{1}>(a) ^ static_cast<{1}>(b));
 }
+inline constexpr {0} &operator|=({0} &a, {0} b) {{
+    return a = a | b;
+}
+inline constexpr {0} &operator&=({0} &a, {0} b) {{
+    return a = a & b;
+}
+inline constexpr {0} &operator^=({0} &a, {0} b) {{
+    return a = a ^ b;
+}
 inline constexpr {0} operator~({0} bits) {{
   // Ensure only bits that can be present in the enum are set
   return static_cast<{0}>(~static_cast<{1}>(bits) & static_cast<{1}>({2}u));