Consolidate GSCAM and GSCA into I-GSCA

[emstruong]

• Ensure that I-GSCA implementation reproduces current implementation of GSCA and GSCA-M
• Archive old GSCA and GSCA-M code
• Replace GSCA and GSCA-M with I-GSCA
• Check if you can re-produce the loadings and path coefficients from ALS, by standardizing the weights, then following the rest of the cSEM algorithm to get loadings and path-coefficients.
• What do "revised for simulation" mean in igsca_sim.m? What is it supposed to be?
• See if we can reproduce matlab results if we standardize weights -> get loadings + path-coefficients via cSEM's normal way.
• Maybe adjust GSCA_m to also be another .approach_weights option and to also require the .disattenuate to be TRUE to run?
• Fix issue regarding models with common factors and composites
• Complete .GSCA_modes functionality and documentation
• X and W$Data are not the same in 00_foreman.R for IGSCA... Why? Does this matter? Can we simplify it?
• Ensure that calculateFIT(), calculateFIT_m() and calculateFIT_s() are all compatible with GSCA_m and GSCA
• Add calculateAFIT()
• Make IGSCA exit early to side-step unnecessary computation using an if (){} statement, but still output a standard foreman() return to maintain compatibility
• Fix calculateReliability() compatibility with IGSCA, GSCA_m and more, if necessary.
• Allow random initial weights in IGSCA. Should it be passed to initializeIgscaEstimates? Or should initializeIgscaEstimates be bypassed?
• Add tests for IGSCA compatibility when a construct only has one indicator (see GSCA_m implementation in calculate_weights.R)
• Allow the estimation of both canonical and nomological composites in I-GSCA
• Appropriate bypasses when only 1 construct of any kind is modelled, no structural model, etc