Fix: Support pseudopotential with dense grid

[sunliang98]

Reminder

• Have you linked an issue with this pull request?
• Have you noticed possible changes of behavior below or in the linked issue?
• Have you explained the changes of codes in core modules of ESolver, HSolver, ElecState, Hamilt, Operator or Psi? (ignore if not applicable)

Linked Issue

Fix #3677

What's changed?

When the radial grid of pseudopotential is too dense, such as 1e-3 in al_lps.cpi, the rhoatm[0] = pow((rhoatm[2] / rhoatm[1]), 1. / (atom->ncpp.r[2] - atom->ncpp.r[1])); (line 362 of module_elecstate/module_charge/charge.cpp) will result in zero, so that the following rhoatm[0] = rhoatm[1] / rhoatm[0] results in infinite.

I have fixed this issue by

1. combine the line 362 and line 364 of module_elecstate/module_charge/charge.cpp to avoid above issue.
2. Add a check to rho[0].
3. Add two integrate tests for LPS (101_PW_lps_pseudopots and 907_OF_LPS).

Any changes of core modules? (ignore if not applicable)

• Example: I have added a new virtual function in the esolver base class in order to ...

[dyzheng]

LGTM

[WHUweiqingzhou]

@Qianruipku, do you have more comments about this PR?