[ABI] Updated instruction DB, operands, and minor API changes

This changeset contains an updated instruction database that brings
ARM32 instructions for the first time. It also updates instruction
database tooling especially for ARM64, which will also be used by
ARM32 generator.

Additionally, new operan has been added, which represents a register
list as used by ARM32 instruction set.

Other minor changes are related to ARM - some stuff had to be moved
to a64 namespace from arm namespace as it's incompatible between
32-bit and 64-bit ISA.

db/base.js

@@ -205,7 +205,7 @@ class Operand {
 
   toString() { return this.data; }
 
-  isReg() { return !!this.reg; }
+  isReg() { return !!this.reg && this.type !== "reg-list"; }
   isMem() { return !!this.mem; }
   isImm() { return !!this.imm; }
   isRel() { return !!this.rel; }
@@ -259,6 +259,20 @@ class Instruction {
     return out;
   }
 
+  get operandCount() {
+    return this.operands.length;
+  }
+
+  get minimumOperandCount() {
+    const count = this.operands.length;
+    for (let i = 0; i < count; i++) {
+      if (this.operands[i].optional) {
+        return i;
+      }
+    }
+    return count
+  }
+
   _assignAttribute(key, value) {
     switch (key) {
       case "ext":