Relicense code to Apache License, Version 2.0

This PR re-licenses the MOM6 source code from the Lesser GNU Public
License, version 3 to Apache License, Version 2.0.  This is done with
the consent of all contributors to the source code.

All source files are now tagged with the following disclaimer.
```
This file is part of MOM6, the Modular Ocean Model version 6.
See the LICENSE file for licensing information.
SPDX-License-Identifier: Apache-2.0
```
All relevent source code, scripts, and macros are now explicitly
identified as part of MOM6.  Configuration files containing scripts,
such as GitHub Actions, have also been tagged.  Any other
configurations, such as model inputs, have been excluded.

Author: marshallward

.github/actions/macos-setup/action.yml

@@ -1,3 +1,7 @@
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
+
 name: 'install-macos-prerequisites'
 
 description: 'Install prerequisites for Mac OS compilation'

.github/actions/ubuntu-setup/action.yml

@@ -1,3 +1,7 @@
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
+
 name: 'install-ubuntu-prerequisites'
 
 description: 'Install prerequisites for Ubuntu Linux compilation'

.github/workflows/verify-linux.yml

@@ -1,3 +1,7 @@
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
+
 name: Linux verification
 
 on: [push, pull_request]

.github/workflows/verify-macos.yml

@@ -1,3 +1,7 @@
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
+
 name: MacOS verification
 
 on: [push, pull_request]

.gitlab-ci.yml

@@ -1,3 +1,7 @@
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
+
 stages:
   - setup
   - builds

.gitlab/mom6-ci-run-gnu-restarts-script.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
 
 sect=none
 clean_stats () { # fn to clean up stats files

.gitlab/mom6-ci-run-gnu-script.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
 
 sect=none
 clean_stats () { # fn to clean up stats files

.gitlab/mom6-ci-run-intel-script.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
 
 sect=none
 clean_stats () { # fn to clean up stats files

.gitlab/mom6-ci-run-pgi-script.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
 
 sect=none
 clean_stats () { # fn to clean up stats files

.gitlab/pipeline-ci-tool.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+# This file is part of MOM6, the Modular Ocean Model version 6.
+# See the LICENSE file for licensing information.
+# SPDX-License-Identifier: Apache-2.0
 
 # Environment variables set by gitlab (the CI environment)
 if [ -z $JOB_DIR ]; then