Feature request: allow user to specify when the plant becomes operational (installation time)

Allow user to specify when the plant becomes operational (installation time)

As discussed in https://github.com/NREL/H2Integrate/pull/310#discussion_r2470579053, it will likely be important for a user to be able to specify when a plant transitions between installation and operation, specified in ProFAST as installation time. The financing costs, revenue, and operational costs are all impacted by the installation time. In #310, the installation time is hardcoded as a single year for the numpy financial model implementation. We should expose this to the user, preferably in a way that will allow the user to specify less than a year, probably in hours.

Proposed solution

If user specifies part of a year, then we can pro-rate the costs and revenues for the partial year.

Alternatives considered

A partial solution would be to allow the user to specify years of installation as an integer, which would be simpler computationally while still providing some flexibility.

Additional context

The issue points to the numpy financial model implementation and the discussion in PR #310; start there and review how installation time is currently hardcoded to one year. Done means exposing a user-configurable installation duration, including sub-year values, with costs and revenues prorated for partial years.