Unify meta and runtime data types

[CPWstatic]

Runtime data types should be a superset of meta data types. We should add INT8 INT16 INT32 FIXED_STRING to runtime data types.

meta

enum PropertyType {
    UNKNOWN = 0,

    // Simple types
    BOOL = 1,
    INT64 = 2,          // This is the same as INT in v1
    VID = 3,            // Deprecated, only supported by v1
    FLOAT = 4,
    DOUBLE = 5,
    STRING = 6,
    // String with fixed length. If the string content is shorteri
    // than the given length, '\0' will be padded to the end
    FIXED_STRING = 7,   // New in v2
    INT8 = 8,           // New in v2
    INT16 = 9,          // New in v2
    INT32 = 10,         // New in v2

    // Date time
    TIMESTAMP = 21,
    DATE = 24,
    DATETIME = 25,
} (cpp.enum_strict)

runtime

    enum class Type {
        __EMPTY__ = 0,
        NULLVALUE = 1,
        BOOL = 2,
        INT = 3,
        FLOAT = 4,
        STRING = 5,
        DATE = 6,
        DATETIME = 7,
        VERTEX = 8,
        EDGE = 9,
        PATH = 10,
        LIST = 11,
        MAP = 12,
        SET = 13,
        DATASET = 14,
    };