Show number of sub-techniques under a given technique

[isaisabel]

As a user of the ATT&CK Navigator, I want to be able to see the number of sub-techniques are under a given technique while the technique is collapsed.

We should modify the technique cell format to include the sub-technique count suffix as used on the ATT&CK Website's matrices:

---

As a user, I also want to be able to tell how many of those sub-techniques have annotations while the parent is collapsed.

This can be done probably by modifying the suffix format. For example,

• a technique with three sub-techniques, two of which are annotated, would be formatted as (3/2).
• A technique with 8 sub-techniques, all of which are annotated, would be formatted as (8/8).
• A technique with 5 sub-techniques, none of which are annotated, would be formatted as (0/5). This should also be deemphasized (displayed with medium/light gray text) so that the user's eyes are drawn to counts where sub-techniques have annotations.

Both counts should exclude disabled sub-techniques.