Allow to easily change the path to cache folder

[bbt-dev]

There are 2 problems with chromium (and also firefox) caching temporary files to the disk:

1. Described in the opened "Save SSD by disabling session restore ou increase session store intervals" issue
2. During regular backups to external disk the huge cache backups also just because it is situated in user profile folder (and during bulk directories backup it is not convenient to introduce excluding paths).

The solution could be rather simple: allow to easily change the path to cache folder.
If Thorium will write the cache to the dedicated disk - this will prevent consuming SSD writing resource, and could easily exclude cache from backups.
The optimal way would be to store cache to a separate second quite medium-performance physical disk, thus the main SSD resource will not be consumed by writing and then deleting the huge amount of cache during browsing. Less favorable solution would be to dedicate a logical disk on the main SSD to write cache, so the same sectors will be consumed but not on the main "C" disk.

I found an article describing how to change the Chrome cache location either by adding '--disk-cache-dir="F:\chrome"' to the browser icon properties or by using "mklink/D" for setting the redirection at the Windows level (thus mklink/D "C:\Users\user\AppData\Local\Google\Chrome\User Data\Default\Cache" "E:\ChromeDownload\Cache" will redirect all files that would be saved in cache folder to the folder at E: drive).
But I am not sure whether these solutions are good and whether they will work for Thorium in the future versions.

So, the best way would be just to have a setting in the Thorium menu that can easily change the folder with cache. The solution would be quite easy to implement.

[Alex313031]

@bbt-dev I could add a flag with a little text box where you can type or copy/paste a path to specify for the cache folder.

UPDATE: Added this and some other to the TODO.md for next releaes > 24dcb9f