Add string conversion for InstructionControlFlowKind enum

Refactor the string conversion of the `lldb::InstructionControlFlowKind` enum out
of `Instruction::Dump` to enable reuse of this logic by the
JSON TraceDumper (to be implemented in separate diff).

Will coordinate the landing of this change with D130320 since there will be a minor merge conflict between
these changes.

Test Plan:
Run unittests
```
> ninja check-lldb
[4/5] Running lldb unit test suite

Testing Time: 10.13s
  Passed: 1084
```

Verify '-k' flag's output
```
(lldb) thread trace dump instructions -k
thread hfinkel#1: tid = 1375377
  libstdc++.so.6`std::ostream::flush() + 43
    7048: 0x00007ffff7b54dab    return      retq
    7047: 0x00007ffff7b54daa    other       popq   %rbx
    7046: 0x00007ffff7b54da7    other       movq   %rbx, %rax
    7045: 0x00007ffff7b54da5    cond jump   je     0x11adb0                  ; <+48>
    7044: 0x00007ffff7b54da2    other       cmpl   $-0x1, %eax
  libc.so.6`_IO_fflush + 249
    7043: 0x00007ffff7161729    return      retq
    7042: 0x00007ffff7161728    other       popq   %rbp
    7041: 0x00007ffff7161727    other       popq   %rbx
    7040: 0x00007ffff7161725    other       movl   %edx, %eax
    7039: 0x00007ffff7161721    other       addq   $0x8, %rsp
    7038: 0x00007ffff7161709    cond jump   je     0x87721                   ; <+241>
    7037: 0x00007ffff7161707    other       decl   (%rsi)
    7036: 0x00007ffff71616fe    cond jump   je     0x87707                   ; <+215>
    7035: 0x00007ffff71616f7    other       cmpl   $0x0, 0x33de92(%rip)      ; __libc_multiple_threads
    7034: 0x00007ffff71616ef    other       movq   $0x0, 0x8(%rsi)
    7033: 0x00007ffff71616ed    cond jump   jne    0x87721                   ; <+241>
    7032: 0x00007ffff71616e9    other       subl   $0x1, 0x4(%rsi)
    7031: 0x00007ffff71616e2    other       movq   0x88(%rbx), %rsi
    7030: 0x00007ffff71616e0    cond jump   jne    0x87721                   ; <+241>
    7029: 0x00007ffff71616da    other       testl  $0x8000, (%rbx)           ; imm = 0x8000
```

Differential Revision: https://reviews.llvm.org/D130580

Author: jj10306

lldb/include/lldb/Core/Disassembler.h

@@ -226,6 +226,9 @@ class Instruction {
 
   virtual bool IsCall() { return false; }
 
+  static const char *GetNameForInstructionControlFlowKind(
+      lldb::InstructionControlFlowKind instruction_control_flow_kind);
+
 protected:
   Address m_address; // The section offset address of this instruction
                      // We include an address class in the Instruction class to

lldb/source/Core/Disassembler.cpp

@@ -577,6 +577,30 @@ AddressClass Instruction::GetAddressClass() {
   return m_address_class;
 }
 
+const char *Instruction::GetNameForInstructionControlFlowKind(
+    lldb::InstructionControlFlowKind instruction_control_flow_kind) {
+  switch (instruction_control_flow_kind) {
+  case eInstructionControlFlowKindUnknown:
+    return "unknown";
+  case eInstructionControlFlowKindOther:
+    return "other";
+  case eInstructionControlFlowKindCall:
+    return "call";
+  case eInstructionControlFlowKindReturn:
+    return "return";
+  case eInstructionControlFlowKindJump:
+    return "jump";
+  case eInstructionControlFlowKindCondJump:
+    return "cond jump";
+  case eInstructionControlFlowKindFarCall:
+    return "far call";
+  case eInstructionControlFlowKindFarReturn:
+    return "far return";
+  case eInstructionControlFlowKindFarJump:
+    return "far jump";
+  }
+}
+
 void Instruction::Dump(lldb_private::Stream *s, uint32_t max_opcode_byte_size,
                        bool show_address, bool show_bytes,
                        bool show_control_flow_kind,
@@ -618,35 +642,10 @@ void Instruction::Dump(lldb_private::Stream *s, uint32_t max_opcode_byte_size,
   }
 
   if (show_control_flow_kind) {
-    switch (GetControlFlowKind(exe_ctx)) {
-    case eInstructionControlFlowKindUnknown:
-      ss.Printf("%-12s", "unknown");
-      break;
-    case eInstructionControlFlowKindOther:
-      ss.Printf("%-12s", "other");
-      break;
-    case eInstructionControlFlowKindCall:
-      ss.Printf("%-12s", "call");
-      break;
-    case eInstructionControlFlowKindReturn:
-      ss.Printf("%-12s", "return");
-      break;
-    case eInstructionControlFlowKindJump:
-      ss.Printf("%-12s", "jump");
-      break;
-    case eInstructionControlFlowKindCondJump:
-      ss.Printf("%-12s", "cond jump");
-      break;
-    case eInstructionControlFlowKindFarCall:
-      ss.Printf("%-12s", "far call");
-      break;
-    case eInstructionControlFlowKindFarReturn:
-      ss.Printf("%-12s", "far return");
-      break;
-    case eInstructionControlFlowKindFarJump:
-      ss.Printf("%-12s", "far jump");
-      break;
-    }
+    lldb::InstructionControlFlowKind instruction_control_flow_kind =
+        GetControlFlowKind(exe_ctx);
+    ss.Printf("%-12s", GetNameForInstructionControlFlowKind(
+                           instruction_control_flow_kind));
   }
 
   const size_t opcode_pos = ss.GetSizeOfLastLine();