message: [language/ir-to-bytecode] rename MoveStruct_ to AstStructDefinition
  The `_` at the end is no longer consistent with our naming scheme, so switch to a clearer scheme.
  Closes:
  Approved by: tnowacki
diff: @@ -9,7 +9,7 @@ use crate::{
  FunctionCall, FunctionCall_, FunctionName, FunctionSignature as AstFunctionSignature,
  FunctionVisibility, IfElse, ImportDefinition, LValue, LValue_, Loc, Loop, ModuleDefinition,
  ModuleIdent, ModuleName, Program, QualifiedModuleIdent, QualifiedStructIdent, Script,
  - Statement, StructDefinition as MoveStruct_, StructDefinitionFields, Type, TypeVar,
  + Statement, StructDefinition as AstStructDefinition, StructDefinitionFields, Type, TypeVar,
  TypeVar_, UnaryOp, Var, Var_, While,
  },
  };
  @@ -546,7 +546,7 @@ fn function_signature(
  fn compile_structs(
  context: &mut Context,
  self_name: &ModuleName,
  - structs: Vec<MoveStruct_>,
  + structs: Vec<AstStructDefinition>,
  ) -> Result<(Vec<StructDefinition>, Vec<FieldDefinition>)> {
  let mut struct_defs = vec![];
  let mut field_defs = vec![];
  