Update request logger to support v2 protocol

[ukclivecox]

What this PR does / why we need it:

• Support the V2 protocol in the request logger

Which issue(s) this PR fixes:

Fixes #2791

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

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[seldondev]

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[seldondev]

Wed Dec 23 14:50:22 UTC 2020
The logs for [lint] [2] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2802/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2802 --build=2

[seldondev]

Wed Dec 23 14:50:43 UTC 2020
The logs for [pr-build] [1] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2802/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2802 --build=1

[ryandawsonuk]

Just comparing this logic to https://github.com/SeldonIO/seldon-core/blob/master/components/seldon-request-logger/app/default_logger.py#L314
In that logic 3 dimensions would be batch tabular. Has me wondering about the assumption there that the first dimension is batch.

[seldondev]

Tue Jan 5 15:57:15 UTC 2021
The logs for [pr-build] [3] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2802/3.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2802 --build=3

[seldondev]

Tue Jan 5 15:57:24 UTC 2021
The logs for [lint] [4] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2802/4.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2802 --build=4

[ukclivecox]

BYTES data fails. But we could leave this until we have a use case.

[ryandawsonuk]

/lgtm
/approve