Incorporate SymmetricSharedBasisMatrix from Hatrix trunk into examples.

[v0dro]

The following people need to use the SymmetricSharedBasisMatrix class from #114 into their respective examples:

• @wawando
• @QxGbM
• @v0dro

EDIT:

Update 3 December 2023 (for @v0dro):

This task is a combination of many tasks where we want to make sure that all the examples make use of the types from within the Hatrix trunk and do not have to define their own types within every file. This can be broken down into the following:

• BLR2_weak_CON - Blr2 weak con #122
• BLR2_strong_CON
• H2_weak_CON_2lev - H2 weak con 2lvl #125
• H2_weak_CON. - HSS multi-level construction. #126
• H2_strong_CON - H2 matrix construction with strong admissibility (fixed rank) #129
• Dense_LU_2x2 - Dense LU 2x2 example uses new Hatrix API. #127
• Dense_QR_2x2 - Dense QR 2x2 #128
• H2_strong_PO
• BLR2_strong_LU
• Dense_LU_NxN
• H2_weak_LDL
• BLR2_weak_LU_2x2_noumv
• H2_strong_LU
• BLR2_weak_LU_noumv
• BLR2_strong_LU_noumv
• Dense_EV
• BLR2_weak_LDL
• BLR2_strong_LDL
• BLR2_weak_LU
• H2_weak_LU
• H2_weak_LU_2lev
• H2_strong_LDL
• H2_strong_LDL_nodep
• H2_strong_PO_nodep
• BLR2_weak_MM_2x2
• BLR2_strong_MM
• BLR2_weak_MM
• H2_weak_MM_2lev
• H2_weak_MM
• H2_strong_EV_sym
• H2_strong_EV_sym_nodep

Ideally, each file should be updated with a separate PR to maintain sanity of merges. The PRs will linked in this issue.