Listening dot CSS classes (#1500)

Add listening dot css classes so that the dots colors can be changed with CSS

example:
```
.yxt-SearchBar-dot1 { fill: red }
.yxt-SearchBar-dot2 { fill: yellow }
.yxt-SearchBar-dot3 { fill: blue }
.yxt-SearchBar-dot4 { fill: green }
```

J=none
TEST=manual

Add some CSS to a search bar page and confirm the colors appear