Pull out the number parsing logic

Pull out the number parsing logic

Pull out the number parsing logic from
AssemblyContext::binaryEncodeNumericLiteral() to utilities.

The new utility function: `ParseAndEncodeNumber()` now accepts:
  * number text to parse
  * number type
  * a emit function, which is a function which will be called with each
    parsed uint32 word.
  * a pointer to std::string to be overwritten with error messages.
    (pass nullptr if expect no error message)
and returns:
  * an enum result type to indicate the status

Type/Structs moved to utility:
  * template<typename T> class ClampToZeroIfUnsignedType

New type:
* enum EncodeNumberStatus: success or error code
* NumberType: hold the number type information for the number to be parsed.
 * several helper functions are also added for NumberType.

Functions moved to utility:
  * Helpers:
    * template<typename T> checkRangeAndIfHexThenSignExtend() -> CheckRangeAndIfHex....()
  * Interfaces:
    * template<typename T> parseNumber() -> ParseNumber()
    * binaryEncodeIntegerLiteral() -> ParseAndEncodeIntegerNumber()
    * binaryEncodeFloatingPointLiteral() -> ParseAndEncodeFloatingPointNumber()
    * binaryEncodeNumericLiteral() -> ParseAndEncodeNumber()

Tests added/moved to test/ParseNumber.cpp, including tests for:
* ParseNumber(): This is moved from TextToBinary.cpp to ParseNumber.cpp
* ParseAndEncodeIntegerNumber(): New added
* ParseAndEncodeFloatingPointNumber(): New added
* ParseAndEncodeNumber(): New added

Note that the error messages are kept almost the same as before, but
they may be inappropriate for an utility function. Those will be fixed
in another CL.