Making the compiler a variant

[pearce8]

Description

On command line, optionally specify "compiler=...." in "system init" to change the compiler.

Dependencies: None.

Fixes issue(s): n/a

Type of Change

• { } Adding a system, benchmark, or experiment
• {X} Modifying an existing system, benchmark, or experiment
• { } Documentation update
• { } Build/CI update
• { } Benchpark core functionality

Checklist:

If adding/modifying a system:

• { } Create a new directory for the system and a new system.py file
• { } Add a new dry run unit test in .github/workflows
• { } System appears in System Specifications table in docs catalogue section

If adding/modifying a benchpark:

• { } Add a new application.py and (maybe) package.py under a new directory
  for this benchmark
• { } Configure an experiment
• { } Benchmark appears in Benchmarks and Experiments table in docs catalogue
  section

If adding/modifying a experiment:

• { } Extend experiment.py under existing directory for specific benchmark
• { } Define a single node and multi-node experiments

If adding/modifying core functionality:

• { } Update docs
• { } Update .github/workflows and .gitlab/ci unit tests (if needed)

[SBA0486]

The string {self.spec.variants["compiler"][0]} is not interpreted and leads to the following error:
Error: Error parsing yaml in "/saxpy-openmp/Fugaku-ffa9e24/workspace/configs/software.yaml", line 4, column 17: expected ',' or '}', but got '['

[pearce8]

@SBA0486 I added quotes, please try again.