[Cata Classic] Add Necrotic Strike Tracker

[Jaesax]

Is your feature request related to a problem? Please describe:

Feature existed from MoP onwards by default, requesting it for cata since beta is not in the greatest state and I doubt its gonna be in.

Describe the solution you'd like to see implemented:

From MoP onwards healing absorbs are shown on the raid frames (See Blue Square, First Picture). Would love to see a implementation of the feature into the addon for Cata Classic
In Cata Classic the exact value of the healing absorb is shown in the debuff tooltip so it does not need to be predictive.

Describe alternatives you've considered:

There are WeakAuras that show the value of the absorb next to the raid frame as a number which are at least IMO very unhandy and implementing the feature requested is a huge QoL for PvPers

Additional context: