This commit brings the Catch2 dependency into the project

Resolve "C API header does not compile with a C compiler"

Closes #12 and #13

See merge request !9

Also make the implementation of ADM_job_requirements_t private to the
library.

Resolve "Add a proper admire API for clients"

This MR provides the initial implementation for the ADMIRE I/O Scheduler API.

Closes #10

See merge request !8

Resolve "Implement stubs for ADMIRE RPCs"

This MR implements basic stubs for the ADMIRE API RPCs for implementation purposes.

Closes #1

See merge request !1