[!59] [gridfactory] Implement insertBoundarySegment.

Merge branch 'feature/insert-boundary-segment' into 'master'

ref:extensions/dune-foamgrid Has to wait for
[core/dune-grid!348] to be
merged.

See merge request [!59]

  [core/dune-grid!348]: core/dune-grid!348
  [!59]: gitlab.dune-project.org/extensions/dune-foamgrid/merge_requests/59
7 jobs for master in 4 minutes and 2 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #106244
duneci
debian:10 clang-7-libcpp-17

00:03:40

passed #106243
duneci
debian:10 gcc-8-noassert-17

00:03:53

passed #106246
duneci
debian:9 clang-3.8-14

00:03:19

passed #106245
duneci
debian:9 gcc-6-14

00:03:21

passed #106249
duneci
dune:2.6 ubuntu:18.04 clang-6-17

00:04:01

passed #106247
duneci
ubuntu:16.04 gcc-5-14

00:03:18

passed #106248
duneci
ubuntu:18.04 clang-6-17

00:03:33