ENH: System independent kernel management and database creation

[alfonsoSR]

Is your feature related to a problem? Please describe

HPLOP has the following set of features regarding SPICE kernels and spherical harmonics coefficients:

• Check if requested kernels are available and download them otherwise.
• Create a metakernel file with requested kernels.
• Check if spherical harmonics coefficients are available and download them otherwise.
• Create an SQL database from a standard csv with spherical harmonics coefficients.

The current implementation of these features makes them system dependent:

• Kernels and coefficients are downloaded using curl.
• Files and directories are created using unix shell commands.

Additionaly, downloaded files are saved to a non-standard location: the directory from which the program is executed.

Describe your suggested solution.

• Download and manage files using functions from Python's standard library.
• Save files to standard locations that work for both unix, and non-unix operating systems.

Alternative approaches.

No response

Additional context

No response

Would you like to implement it?

• I want to give it a try.