Implemented TNA Register in core_tna.p4 for sampling of Telemetry Reports

[spisarski]

Fixes #153

What does this PR do?

Implements a TNA extern called a "Register" where we can keep track of each potential packets to mirror so we can configure the "mirror_sampler" register to mirror out every or on in every nth packet for generation of Telemetry Reports.

Do you have any concerns with this PR?

no

How can the reviewer verify this PR?

If the data-inspection tests are run and the TpsCoreIngress.mirror_sampler table's "rate" field has a value other than 0, the tests that count packets on the "clone" machine will fail. If the "rate" is '1', every other packet will be mirrored, '2', every third, etc.

Any background context you want to provide?

We need this functionality for the lab trial as the Telemetry Reports could overwhelm the network and AEs under load.

Screenshots or logs (if appropriate)

Questions:

• Have you connected this PR to the issue it resolves? yes #153
• Does the documentation need an update? Eventually, but only after we address #328
• Does this add new dependencies? no
• Have you added unit or functional tests for this PR? no, see #328

[spisarski]

Run Tofino aggregate build

[spisarski]

Run Tofino aggregate build

[spisarski]

Run Tofino aggregate build

[spisarski]

Run Tofino aggregate build