Add support for "% increased cast speed if a minion has been killed recently"

[spawnie-no-oni]

Fixes #4455 .

Description of the problem being solved:

Ghastly Eye Jewel can have a mod that reads "d% increased cast speed if a minion has been killed recently". From in-game testing this seems to proc under exactly the same conditions as "if a minion died recently".

However, the mod does not get parsed by POB because we only look for the string "if a minion died recently". It is inconvenient because any build that relies on this jewels needs manually modify them each time they are imported to calculate their cast speed properly.

Steps taken to verify a working solution:

• Create a new build
• Path to a jewel socket
• Create a custom item with the following stats
  Enthralling Leer
  Ghastly Eye Jewel
  Unique ID: 437aad3ec28997fc919c9d100102fb765eb5ca2a27b28d2bafa334010211790a
  Item Level: 74
  LevelReq: 28
  Implicits: 0
  +30 to maximum Life
  Minions have 12% increased maximum Life
  7% increased Cast Speed if a Minion has been Killed Recently
• Socket it into the Jewel socket.
• Below configuration, tick "has a minion died recently ?".
• Add any spell skill to the build (in my case SRS)
• Check that the cast speed is modified when allocating and deallocating the jewel.

Link to a build that showcases this PR:

https://pastebin.com/V7jw0HJH

Before screenshot:

After screenshot: