Add func StringMapE

[shockerli]

func

func StringMapE(val interface{}) (m map[string]interface{}, err error)

feature

• Support JSON string of map

// input
`{"name":"cvt","age":3.21}`

// expect
map[string]interface{}{"name": "cvt", "age": 3.21} 

• Support any map type

// input
map[interface{}]interface{}{111: "cvt", "222": 3.21}

// expect
map[string]interface{}{"111": "cvt", "222": 3.21}

• Support any struct type

// input
struct {
    Name string
    Age  int
}{"cvt", 3}

// expect
map[string]interface{}{"Name": "cvt", "Age": 3}