Release a 2nd wave of Backport packages

Description

I think we are really close to release the second wave of Backport Packages. We accumulated a number of changes already and few more are about to be completed so that we are, I think, close to release the second wave.

** What will be in those packages **

Everything that is currently merged to the master branch in “providers” package will be included.

Those are open issues that we know we should merge before though:

• ~Enabling cncf.kubernetes provider after 1.10.11/1.10.12 backported changes and spark-on-kubernetes operator~ - this is deferred to the next backport release as per #11298
• Implementing Impersonation for all applicable Google operators (@olchas works on it with Hooks already merged)
• DataProc operator improvements (@turbaszek works on it in #9593 )
• Improve idempotency of BigQueryInsertJobOperator (@turbaszek works on it in #9590)
• Release 1.10.12 of Airflow as it fixes some teething problems with Kubernetes refactor from 1.10.11
• Fix BigQuery operators problem with serialization #10171
• AWS SES #10004
• Fix the DLP operators.
• ~finalize and implement the #10822 allowing to release 1.10.13 with support to auto-dicover provider capabilities such as connections and extra links~ deferred to another release
• ~Merge #10488 with Kerberos on Presto change.~ deferred to the next release
• ~Breaking changes: Email operator moved to Core: we are going to address it in 1.10.13 by adding email provider there and releasing provider package via #11178~

We have to make the following adjustments to the process:

• make sure that we only release the packages that have some changes #back #10375
• make sure to add changes from the previous releases - not only commits but add mechanism to add backwards-incompatible changes akin to UPDATING.md #10376

Update: The second wave is delayed a bit (but coming soon). The reason is two-fold

• the cncf.kubernetes package has a problem that we are solving
• we might try to get the mechanism of separate providers packages and “discovery” mechanism before we build the packages - see the #10822 and #10823

Use case / motivation

We want the users of airflow 1.10 to benefit from fixes and improvements in the latest packages.

[mik-laj]

RC1 packages have been released. Feel free to test and report problems. https://lists.apache.org/thread.html/r4dfc18d2376601667efe7dfaf0bf1c07b840f9bcd9f6311d48cb3c64%40<dev.airflow.apache.org>

[mik-laj]

Yes. It is planned.