## Why
Frequently used; top in perf profile
## Changes
Most of the time, you already have the claim object in the current context. `selectClaimIsMineForUri` will retrieve the claim again, which is wasteful, even if it is memoized (looking up the cache still takes time).
Break apart the logic and added the alternative `selectClaimIsMine` for faster lookup.
## Issue
`normalizeUri` | `parseURI` is expensive and has been causing sluggish operations when called repeatedly or within a loop.
## Change
Since I'm not confident enough to remove the call entirely from makeSelectClaimIsMine (although I've yet to find a scenario that the uri is not already normalized), we'll try caching the calls instead.
## Results
- in a simple test of toggling between 2 category pages, we saved 20ms from `parseURI` calls alone.
- in a test of opening all categories one time, the memory usage remained similar. This makes sense since we removed a `makeSelect*` (which creates a selector for each call + not memoizing), and replaced that with a cached selector that's actually memoizing.
## Issue
6236 Add context menu to file page
## Notes
The download button actually handles a lot of things -- generating 'streamingUrl', differences between Web and Desktop, download progress for Desktop, etc. A simpler fix would be to put something else (maybe "Share") into the overflow menu instead.
Anyway, went ahead to do it per 6236, but retained the item for Desktop since we need a progress label.
## Issue
The removal of `svg` from `media__subtitle` in 09b689ba made the icon black.
## Fix
Both 'Open File' and 'Download' should have the same css class.
* am I done?
* post diff
* unused selector cleanup
* missed commit
* mess with button styles
* fix flow
Co-authored-by: Jeremy Kauffman <jeremy@lbry.io>
Co-authored-by: Sean Yesmunt <sean@lbry.io>
