XAxis type in LineConfig is fixed as ValueCatTimeAxis

### Is your feature request related to a problem? Please describe.
if want to set line data like [(1,1),(2,2)...] what type should we use? it's not the datetime type

### Describe the solution you'd like
we should use dynamic type as XAxis setting.

### Additional context
for Shinese：
在line配置中XAxis固定为 ValueCatTimeAxis，是不是把x轴的类型固定为时间类型了，
如果像展示x的是[1,2,3,4...10]这种类型，如何使用呢？