Filter: Neighborhoods/Community Org/Zone Pills: Unable to clear the pills using screen readers

## Description
Tracy Note: This ticket is related to https://github.com/CodeForPhilly/clean-and-green-philly/issues/631 & probably would be fixed with that refactor to pull out the selected pills from the dropdown.

Clearing the pills is impossible using NVDA & Voice Over. JAWS is more forgiving.

- NVDA + FF/Edge: Using tab key to navigate to the X button, selecting it activates the listbox pop up instead

Demo; see **from point 2:18** of the video onwards.

https://github.com/CodeForPhilly/clean-and-green-philly/assets/102739972/ade5b3b2-ca41-4165-ac9f-6bbbb8ca462c

- VO + Safari: Screen reader focus could not navigate to the pills at all; no feedback given when tabbing to it.

## Recommendation
- Would be better to not put the pill on top of the listbox popup so that there's a clear separation between the 2. It will also make the UI less confusing even for sighted users.

首先使用 NVDA 在 Firefox/Edge 上以及 VoiceOver 在 Safari 上复现 filter-pill 的行为，并以 issue 631 作为相关重构的背景。完成标准是，屏幕阅读器用户无需意外激活 listbox，即可访问、理解并清除 Neighborhoods、Community Org 和 Zone pill。

由索引模型根据 Issue 内容生成。