Passed investigation times to the classical risk and bcr calculators

[micheles]

Closes https://github.com/gem/oq-engine/issues/7927.

AR edit — Summary of steps:

• From hazard curve, get probabilities of exceedance in investigation_time
• Numerical differentiation to get hazard probabilities of occurrence in investigation_time
• [Added in this PR] Convert to annual frequencies of occurrence
• Convert vulnerability distribution to a loss ratio exceedance matrix
• [Added in this PR] Get loss ratio annual frequencies of exceedance
• [Added in this PR] Convert back to loss ratio probabilities of exceedance in risk_investigation_time

Specs - Classical PSHA-Based Risk Calculator.pdf