[WIP] Add support for Fortran Package Manager

[ivan-pi]

These changes allow the use of the Fortran package manager. (preCICE needs to be installed separately however)

~/fortran/fortran-module$ fpm build --link-flag "-L/usr/local/lib/"
 + mkdir -p build/dependencies
precice.f90                            done.
libprecice-fortran-module.a            done.
solverdummy.f90                        done.
solverdummy                            done.
[100%] Project compiled successfully.

Other projects could then use this module as a dependency, by adding the following to their manifest:

[dependencies]
precice-fortran-module.git = "https://github.com/precice/fortran-module"

and making sure libprecice.* is available in the compiler search path.

Work remaining:

• finalize manifest
• build example using the setup-fpm action

[ivan-pi]

The main changes are:

• adding the fpm.toml manifest file
• moving precice.f90 into the src/ folder (fpm expects a canonical layout)

(Sorry I mistakenly based this off the wrong branch, hence the one extra commit).

[ivan-pi]

Suggested change

	author = "Jane Doe"
	maintainer = "jane.doe@example.com"
	copyright = "Copyright 2021, Jane Doe"
	description = "precice Fortran module"
	homepage = "https://precice.org/index.html"
	author = "preCICE developers"
	maintainer = "info@precice.org"
	copyright = "Copyright 2024, preCICE developers"
	description = "preCICE Fortran module"
	homepage = "https://precice.org/"

[ivan-pi]

Suggested change

	name = "precice-fortran-module"
	version = "0.1.0"
	license = "license"
	name = "precice-fortran-module"
	license = "LGPL-3.0"

[ivan-pi]

ToDo list:

• change folder path in Makefile
• adapt CI and examples
• add fpm usage to README
• versioning (new issue)