* viz: add data-plane and prometheus healthchecks
Fixes#5325
This branch adds the remaining healthchecks for the viz extension
i.e
- Data-plane metrics check in Prometheus
- `--proxy` mode which also checks for tap injections based
on annotations.
For this, The following changes were needed
- Category.ID is made public so that --proxy toggleness can be
allowed
- Made tap env key as a field so that it can be re-used for
checks
simplify viz.NewHealthChecker by removing the need to
pass categoryIDs and instead using
hc.appendCategories directly at the caller to add the
required categories. This is possible by dividing the vizCategories
into separate functions
Signed-off-by: Tarun Pothulapati <tarunpothulapati@outlook.com>