[C + B] Add methods to control number of arrows on player.  Adds BUKKIT-3721

**The Issue:**
There is currently no method of getting or altering the number of arrows displayed on the client as stuck in the player.

**PR Breakdown:**
This PR, in conjuncture with its CraftBukkit PR counterpart, adds this functionality, allowing developers to take advantage of it as they please.

**CraftBukkit PR:**
https://github.com/Bukkit/CraftBukkit/pull/1217

**JIRA Ticket:**
https://bukkit.atlassian.net/browse/BUKKIT-3721