crucible-llvm-syntax: Concrete syntax for remaining LLVM syntax formers

[langston-barrett]

#1113 introduced support for parsing syntax that corresponds to some of the constructors of LLVMExtensionExpr and LLVMStmt. We should extend this parser with syntax for all of these constructors:

LLVMExtensionExpr

• X86Expr
• LLVM_SideConditions
• LLVM_PointerExpr (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)
• LLVM_PointerBlock (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)
• LLVM_PointerOffset (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)
• LLVM_PointerIte (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)

LLVMStmt:

• LLVM_PushFrame
• LLVM_PopFrame
• LLVM_Alloca (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)
• LLVM_Load (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)
• LLVM_Store (crucible-llvm-syntax: Concrete syntax for Crucible-LLVM #1113)
• LLVM_MemClear
• LLVM_LoadHandle (crucible-llvm-cli: Support for overrides; loading and calling functions #1125)
• LLVM_ResolveGlobal (crucible-llvm-cli: Support for overrides; loading and calling functions #1125)
• LLVM_PtrEq
• LLVM_PtrLe
• LLVM_PtrAddOffset (crucible-llvm-syntax: Parse addition and subtraction of pointers #1146)
• LLVM_PtrSubtract (crucible-llvm-syntax: Parse addition and subtraction of pointers #1146)
• LLVM_Debug