[Refactor] Introduce NeuraAttributes.h to manage attribute constants

[shiyunyao]

This PR addresses part of #145 by introducing a centralized header NeuraAttributes.h and replacing a subset of hardcoded magic strings in the lib/ directory.

[tancheng]

Thanks for the cleanup~!

[tancheng]

Can we also have following in the header file?

dataflow/lib/NeuraDialect/Transforms/GenerateCodePass.cpp

Lines 204 to 224 in 2a6fdfa

	// Literals for CONSTANT operations, e.g. "#10" / "#0" / "#3.0".
	static std::string getConstantLiteral(Operation *op) {
	if (isConstant(op)) {
	if (auto value_attr = op->getAttr("value")) {
	std::string result = extractConstantLiteralFromAttr(value_attr);
	if (!result.empty()) return result;
	}
	return "#0";
	}
	// Checks for constant_value attribute in non-CONSTANT operations.
	if (auto constant_value_attr = op->getAttr("constant_value")) {
	std::string result = extractConstantLiteralFromAttr(constant_value_attr);
	if (!result.empty()) return result;
	}
	// Checks for rhs_value attribute (for binary operations with constant RHS).
	if (auto rhs_value_attr = op->getAttr("rhs_value")) {
	std::string result = extractConstantLiteralFromAttr(rhs_value_attr);
	if (!result.empty()) return result;
	}

And anything introduced from https://github.com/coredac/dataflow/pull/157/changes

[shiyunyao]

Hi @tancheng, thanks for the suggestions!

I have addressed both points in the latest commits:

1. Clarified Dataflow/Mapping modes: Added comments as requested (see b209ad1).

2. Added missing constants: Ported the logic from GenerateCodePass.cpp and added kValue, kConstantValue, kRhsValue, kLhsValue to the header (see 344e97c).

Please verify and resolve the conversation if it looks good.

[tancheng]

Thanks~!