Backport of openvpn for jammy, noble and questing

[Lena Voytek]

[Impact]

This bug tracks an update for the OpenVPN package, moving to versions:

* <list of Ubuntu series and stable versions being introduced>

See https://wiki.ubuntu.com/OpenVPNUpdates

These updates are a best effort to only include bug fixes, following the
SRU policy exception defined at https://wiki.ubuntu.com/OpenVPNUpdates.

Note that openvpn does not have an accepted micro-release
exception. However, the SRU team has agreed to consider further releases
given a full knowledge and possible mitigation of backwards-incompatible
changes. See
https://lists.ubuntu.com/archives/ubuntu-release/2023-July/005688.html

[Major Changes]

* <list of series with link to release notes>
  - <Important bug fixes>
  - <CVEs fixes added, and note whether or not already applied in ubuntu>

[Test Plan]

See https://wiki.ubuntu.com/OpenVPNUpdates#QA

DEP-8 Tests:
server-setup-with-ca - creates and tests an OpenVPN server setup with its own certificate authority
server-setup-with-static-key - creates and tests an OpenVPN server setup using a static key for authentication

<links to autopkgtest results for this backport>
<discussion of test results>

[Regression Potential]

Upstream has an extensive build and integration test suite. So
regressions would likely arise from a change in interaction with
Ubuntu-specific integrations.

<additional details about areas to watch for regressions>

[Other Info]

This is a recurring effort. For reference, here are previous OpenVPN SRU backports:

* <List LP: #bug links to former cases of SRU backports for this package>