add query string param and path param into header and context

[caevv]

Description of changes:

Add API gateway path parameters and query string parameters into the header and context.

More important on this PR is the Path Parameter as this cannot be extracted any other way, happy to remove the query string parameter.

[sapessi]

What's the use-case for getting path parameters this way and not through the framework itself? For example in gin you'd write:

router.GET("/user/:name/*action", func(c *gin.Context) {
        name := c.Param("name")
        action := c.Param("action")
        message := name + " is " + action
        c.String(http.StatusOK, message)
    })```

[drakejin]

@sapessi Do you think It's not aws-lambda-go-api-proxy's responsibility to directly manipulate path and query parameters?

Therefore, You recommend using well-known HTTP frameworks for manipulating path or query parameters. isn't it?