This commit decouples XC_Functional and related libxc functions from the global PARAM object by adding explicit parameters:

1. Modified XC_Functional::v_xc() to accept nspin, domag, domag_z parameters instead of accessing PARAM
2. Modified XC_Functional::gradcorr() to accept nspin, domag, domag_z parameters
3. Modified XC_Functional::set_xc_type() to accept nspin parameter
4. Modified XC_Functional_Libxc::v_xc_libxc() to accept nspin, domag, domag_z parameters
5. Modified XC_Functional_Libxc::v_xc_meta() to accept nspin parameter

Updated all call sites in:
- source_estate/module_pot/pot_xc.cpp
- source_estate/module_pot/pot_xc_fdm.cpp
- source_pw/module_pwdft/forces_cc.cpp
- source_pw/module_pwdft/stress_cc.cpp
- source_hamilt/module_xc/xc_pot.cpp
- source_hamilt/module_xc/libxc_pot.cpp
- source_hamilt/module_xc/libxc_abacus.h

Updated test files to remove PARAM dependencies:
- test_xc3.cpp: Removed PARAM include and initialization
- test_xc5.cpp: Removed PARAM include and initialization, updated v_xc, v_xc_meta calls
- xctest.h: Removed PARAM include and initialization

Default parameter values are provided for backward compatibility.

…prove parameter passing

Summary of changes:

1. Modified libxc_abacus.h:
   - Removed default value (=1) for nspin parameter in v_xc_libxc
   - Removed default value (=nullptr) for scaling_factor parameter in v_xc_libxc

2. Modified xc_functional.h:
   - Changed set_xc_type signature to only accept const std::string xc_func_in
   - Removed nspin and basis_type parameters from set_xc_type
   - Removed default parameters from v_xc and gradcorr

3. Modified xc_functional.cpp:
   - Updated set_xc_type implementation to match new signature
   - Removed meta-GGA nspin=4 check from set_xc_type (moved to gradcorr)
   - Removed hybrid functional LCAO check from set_xc_type (no longer needed)
   - Updated internal set_xc_type calls to use single parameter

4. Modified xc_grad.cpp:
   - Added meta-GGA nspin=4 check at the beginning of gradcorr function
   - This is the correct place for runtime validation since nspin is known here

5. Modified xc_pot.cpp:
   - Updated v_xc_libxc call to pass parameters correctly

6. Modified libxc_pot.cpp:
   - Updated v_xc_libxc implementation to match new signature

7. Modified stress_gga.cpp:
   - Changed direct 'true' argument to named variable 'is_stress' for gradcorr call
   - Improved code readability and maintainability

8. Updated all set_xc_type call sites (12 files):
   - test_xc.cpp, test_xc1.cpp, test_xc2.cpp, test_xc3.cpp, test_xc5.cpp
   - xc_functional.cpp, esolver_double_xc.cpp, esolver_ks_lcaopw.cpp
   - esolver_fp.cpp, Exx_LRI_interface.hpp, xc_kernel.cpp, exx_helper.cpp
   - All calls now pass only the xc_func_in parameter

9. Updated test_xc3.cpp and test_xc5.cpp:
   - Added named variables (nspin1, nspin2, nspin4, domag, domag_z, domag_true)
   - Removed direct numeric literals in function calls

Rationale:
- Separated functional setup (set_xc_type) from runtime configuration (nspin, basis_type)
- Runtime validation checks moved to actual computation functions (gradcorr)
- Parameter passing improved with meaningful variable names instead of magic numbers
- Code readability and maintainability enhanced
- Preparation for future improvements to XC functional interface