Fix connection costs not properly factored in or discounted

[BenWinchester]

Description

This pull request is being opened to address the issue whereby connection costs for households were only factored in for additional households added to the community in subsequent years and not for initial connections.

For example, with the default location of Bahraich, the community starts with 100 households and then expands throughout the simulation and optimisation periods. However, the cost for connecting these households to the mini-grid network is only included for the additional houses which are created throughout the lifetime of the simulation and not for the initial 100 households. Hence, all results in CLOVER under-report on the total cumulative system cost and the LCUE values.

This will be merged into the development branch and will be publicly released as part of CLOVER 5.2 or CLOVER 6. Hence, the version it is being merged into is 5.2.0a7.

Linked Issues

This pull request:

• closes 225 (Connection costs not properly factored in or discounted #225)
• resolves 195 (Connection costs not properly factored in or discounted #195 in the discussions pages)
• closes 154 (Connection costs not properly factored in or discounted  #154 was the issue originally opened for this 🐛)

Unit tests

This pull request:

• modifies the integration testing as all of the cumulative costs and LCUE values have increased as a result of including these additional hosueholds.