Add devcontainer

[yutaro-sakamoto]

This pull request introduces a variety of changes to the development environment setup, static analysis workflow, and code formatting for the OpenSource COBOL 4J project. The most important changes include setting up a new development container, updating the static analysis workflow to use almalinux, and switching from Google Java Format to Spotless for code formatting.

Development Environment Setup:

• .devcontainer/Dockerfile: Added a new Dockerfile based on almalinux:9 with necessary dependencies for building and testing the project.
• .devcontainer/boot.sh: Added a script to build and install the project, and set up a pre-commit hook for formatting.
• .devcontainer/devcontainer.json: Added configuration for the development container to use the new Dockerfile and boot script.

Static Analysis Workflow:

• .github/workflows/static-analysis.yml: Updated the workflow to use almalinux:9 container and install dependencies using dnf instead of apt-get. [1] [2] [3]

Code Formatting:

• libcobj/app/build.gradle.kts: Replaced Google Java Format with Spotless for code formatting because the behaviour of the old formatter is unstable. [1] [2]
• format: Updated the format script to use Spotless.
• check-format: Updated the check-format script to use Spotless.

Code Cleanup:

• cobj/codegen.c: Removed unused variable extrefs and commented out an unused struct member. [1] [2] [3] [4] [5]
• cobj/cpp-check: Added suppressions for unused struct members and other warnings in cppcheck.

Format C files and Java files with new formatter in the Devcontainer

clang-format and a new formatter spotless formated all C files and Java files in the development environment.

[yutaro-sakamoto]

@tsh-hashimoto @kio-watanabe Please read CONTRIBUTING.md or CONTRIBUTING_JP.md and create a new development environment. This is the highest priority task related to opensource COBOL 4J.

As explained in CONTRIBUTING.md, I suggest that we use Dev Containers of Visual Studio Code as a standard development environment. If you success to create a new development environment and find no issue, please aprove reviews I requested. Otherwise, please give me your questions and suggestions.

[tsh-hashimoto]

Just in case...

4. Clone the repository

Is it alright to clone the repository yutaro-sakamoto:add-devcontainer? (It may a temporary concern. Once your changes are merged, It will not to be necessary to worry about)

[yutaro-sakamoto]

@tsh-hashimoto Yes, you can clone yutaro-sakamoto:add-devcontainer.

Prepare an opensource COBOL 4J repository with the contents of the yutaro-sakamoto:add-devcontainer branch, either by git clone or git checkout.

[tsh-hashimoto]

Thanks. It seemed to be able to set up the Docker environment.

I'll approve this PR.

[yutaro-sakamoto]

@kio-watanabe I have merged this pull request because @tsh-hashimoto verified that the new development environment worked. Please try to create the new development environment on your machine.