Add I/O for determinants

[q-posev]

Determinants are stored as lists of int64 bit fields for up- and down-spin electrons. CI coefficients are stored per state, namely one has to use trexio_set_state(file, state_id) function to read/write CI coefficients of state state_id.

Also implemented helper functions trexio_to_orbital_list and trexio_to_orbital_list_up_dn functions to convert a given determinant into a list of orbitals per spin component and for both components, respectively.

Added groups:

• state
• determinant

Note:

• One of the commits closes Warnings when compiling #90

[scemama]

Awesome!