[BPO] libreoffice 7.4.7 for bionic, focal and jammy

[Impact]

 * LibreOffice 7.4.7 is in its seventh bugfix release of the 7.4 line:
     https://wiki.documentfoundation.org/ReleasePlan/7.4#7.4.7_release

 * This source packages matches the proposed SRU for kinetic handled at
     https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/2018600
   and its backport is currently provided by the LibreOffice Still PPA at
     https://launchpad.net/~libreoffice/+archive/ubuntu/libreoffice-still/+packages

[Scope]

 * Backport of https://launchpad.net/ubuntu/+source/libreoffice/1:7.4.7-0ubuntu0.22.10.1

 * Backport targets are the Bionic/18.04, Focal/20.04 and Jammy/22.04 LTS releases to provide an official build of a more recent upstream version of LibreOffice

[Testing]

 * Upstream testing. Bugs fixed upstream typically include unit/regression tests, and the release itself is extensively exercised (both in an automated manner and manually).

  * A recent set of upstream's automated jenkins testing can be found here:
    https://ci.libreoffice.org/job/gerrit_74/1827/

  * More information about the upstream QA testing can be found here:
    * Automated tests
      https://wiki.documentfoundation.org/QA/Testing/Automated_Tests
    * Automated UI tests
      https://wiki.documentfoundation.org/Development/UITests
    * Regression tests
      https://wiki.documentfoundation.org/QA/Testing/Regression_Tests
    * Feature tests
      https://wiki.documentfoundation.org/QA/Testing/Feature_Tests

 * Launchpad testing. The libreoffice packages include autopkgtests that were run and verified as passing.

   Bionic/18.04 build at https://launchpad.net/~libreoffice/+archive/ubuntu/libreoffice-still/+sourcepub/14738812/+listing-archive-extra
    * [amd64] https://autopkgtest.ubuntu.com/results/autopkgtest-bionic-libreoffice-experimental/bionic/amd64/libr/libreoffice/20230509_091428_b3633@/log.gz
    * [arm64] https://autopkgtest.ubuntu.com/results/autopkgtest-bionic-libreoffice-experimental/bionic/arm64/libr/libreoffice/20230510_174443_fea7f@/log.gz
    * [armhf] https://autopkgtest.ubuntu.com/results/autopkgtest-bionic-libreoffice-experimental/bionic/armhf/libr/libreoffice/20230509_113953_615bf@/log.gz
    * [i386l] https://autopkgtest.ubuntu.com/results/autopkgtest-bionic-libreoffice-experimental/bionic/i386/libr/libreoffice/20230509_111407_9f2bc@/log.gz
    * [ppc64el] https://autopkgtest.ubuntu.com/results/autopkgtest-bionic-libreoffice-experimental/bionic/ppc64el/libr/libreoffice/20230509_110221_c7d8a@/log.gz
    * [s390x] https://autopkgtest.ubuntu.com/results/autopkgtest-bionic-libreoffice-experimental/bionic/s390x/libr/libreoffice/20230311_013952_49140@/log.gz

   Focal/20.04 build at https://launchpad.net/~libreoffice/+archive/ubuntu/libreoffice-still/+sourcepub/14738813/+listing-archive-extra
    * [amd64] https://autopkgtest.ubuntu.com/results/autopkgtest-focal-libreoffice-libreoffice-still/focal/amd64/libr/libreoffice/20230508_165949_20fb6@/log.gz
    * [arm64] https://autopkgtest.ubuntu.com/results/autopkgtest-focal-libreoffice-libreoffice-still/focal/arm64/libr/libreoffice/20230508_213248_aef40@/log.gz
    * [armhf] https://autopkgtest.ubuntu.com/results/autopkgtest-focal-libreoffice-libreoffice-still/focal/armhf/libr/libreoffice/20230508_193232_364c7@/log.gz
    * [ppc64el] https://autopkgtest.ubuntu.com/results/autopkgtest-focal-libreoffice-libreoffice-still/focal/ppc64el/libr/libreoffice/20230508_173145_777fc@/log.gz
    * [s390x] https://autopkgtest.ubuntu.com/results/autopkgtest-focal-libreoffice-libreoffice-still/focal/s390x/libr/libreoffice/20230510_092544_49ed4@/log.gz

   Jammy/22.04 build at https://launchpad.net/~libreoffice/+archive/ubuntu/libreoffice-still/+sourcepub/14738814/+listing-archive-extra
    * [amd64] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-libreoffice-still/jammy/amd64/libr/libreoffice/20230508_203244_68a30@/log.gz
    * [arm64] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-libreoffice-still/jammy/arm64/libr/libreoffice/20230508_201428_74484@/log.gz
    * [armhf] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-libreoffice-still/jammy/armhf/libr/libreoffice/20230508_200026_a1551@/log.gz
    * [ppc64el] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-libreoffice-still/jammy/ppc64el/libr/libreoffice/20230508_182200_559ad@/log.gz
    * [s390x] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-libreoffice-still/jammy/s390x/libr/libreoffice/20230510_045054_7b793@/log.gz

 * General smoke testing of all the applications in the office suite were carried out by going through the manual testplan as documented by: https://wiki.ubuntu.com/Process/Merges/TestPlans/libreoffice

[Regression Potential]

 * A combination of autopkgtests and careful smoke testing as described above should provide reasonable confidence that no regressions sneaked in.