Encapsulate HDF5 module (#5031)

Description of changes:
- bump version requirements of h5xx
- source h5xx via FetchContent instead of submodules
   - the ESPResSo repository can now be cloned without `--recursive`
   - the creation of GitHub releases no longer depends on third-party tools and can be fully automated
- hide hdf5 and h5xx header files and compiler flags from consumer targets
- fix portability issues revealed by newer compiler toolchains

.gitlab-ci.yml

@@ -12,15 +12,13 @@ stages:
     - trying.tmp
   before_script:
     - git config --global --add safe.directory ${CI_PROJECT_DIR}
-    - git config --global --add safe.directory ${CI_PROJECT_DIR}/libs/h5xx
   timeout: 1h
   interruptible: true
 
 .notification_job_template: &notification_job_definition
   <<: *global_job_definition
   image: ghcr.io/espressomd/docker/fedora:f7f8ef2c0ca93c67aa16b9f91785492fb04ecc1b
   variables:
-    GIT_SUBMODULE_STRATEGY: none
     GET_SOURCES_ATTEMPTS: 3
   before_script:
     - git config --global --add safe.directory ${CI_PROJECT_DIR}
@@ -32,7 +30,6 @@ stages:
     - no-cuda
 
 variables:
-  GIT_SUBMODULE_STRATEGY: recursive
   GET_SOURCES_ATTEMPTS: 3
   CCACHE_DIR: /cache
   CCACHE_MAXSIZE: 100G
@@ -49,14 +46,11 @@ style:
   dependencies: []
   before_script:
     - git config --global --add safe.directory ${CI_PROJECT_DIR}
-    - git submodule deinit .
   script:
     - sh maintainer/CI/fix_style.sh
   tags:
     - espresso
     - no-cuda
-  variables:
-    GIT_SUBMODULE_STRATEGY: none
   artifacts:
     paths:
     - style.patch

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "libs/h5xx"]
-	path = libs/h5xx
-	url = https://github.com/h5md/h5xx.git