rebuild `filter-line` as totally non a11y compliant

[philli-m]

filter and sorting elements we use for blog and academy is custom built and is not interpreted by SR's at all, have added label as interim solution but should be rebuilt with as much standard html as possible.
https://stage.liqd.net/en/liquid-academy/
https://stage.liqd.net/en/blog/

[philli-m]

@maxliqd refactor issues are a little tricky as it's more a dev reminder then a PM release issue (sorry know that's a bit complicated, will look at improving the descriptions of the labels). Refactoring is normally something we do when we have a US that touches that piece of code and we have the refactor issue as a reminder but re-writing a piece of code without an existing US normally it out of the work scope of an issue have added a feature request tag so it's clearer how much work it'll be.

Also I have already done a hotfix of adding aria-labels, it's just hacky so would be better to refactor when we have to touch this code anyway

[maxliqd]

@phillimorland Thanks or the explanation, I really appreciate it! Will remove it from the release 22 milestone.