Move solver info loading form NekSys (and its derived classes) to the callers

Issue/feature addressed

A NekSys object should focus on solving system based on the given infos (via NekSysKey). It should not load parameter from sessions, instead, the caller should be responsible for loading the parameter, setting the key and pass it to NekSys constructor.

Proposed solution

Move solver info loading from NekSys (and its derived classese) to the callers.

Implementation

The callers includes GlobalLinSysIterativeFull GlobalLinSysIterativeStaticCond and CFSImplicit. Please notify me if there are other classes that should load info and set keys.

Tests

Suggested reviewers

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Notes

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Checklist

• [ ] Functions and classes, or changes to them, are documented.
• [ ] User guide/documentation is updated.
• Changelog is updated.
• [ ] Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• [ ] License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).