Add resources download button + click to download picker in replay (#469)

Fixes #467 
- Add a download button on the resource page for each entry to allow
downloading each resource no matter what type.
- Add a new 'click to download' image or media picker that allows
highlighting + clicking on image/media to download on the page (to get
around 'Save Image As...) not working. Also supports inline svgs +
background images - should work better than Save Image As...
- Location bar shows a popup indicating in 'click to download' mode,
which can be canceled. Otherwise, mode remains until user downloads
something.
- Type fixes: Untangle Page and URLResource types for better type
checking.
- Deps: bump to wabac.js 2.25.1 for new download mode support

---------
Co-authored-by: Tessa Walsh <tessa@bitarchivist.net>

CHANGES.md

@@ -2,6 +2,12 @@
 
 ## CHANGES
 
+*From release 2.4.0+, changes will now be listed in the release notes on GitHub.*
+*Please see [the list of releases](https://github.com/webrecorder/replayweb.page/releases) for an up-to-date
+list of changes for each release.*
+
+---
+
 v2.3.23
 
 - Fidelity: Fix possible regression from different JS parser in wabac.js, additional XHR improvements (viw abac.js 2.24.5)