Added ring modulator and test

[alexsludds]

This pull request adds a ring modulator device that includes accurate models of the time dynamics/optical peaking of the ring.

Values are set to reasonable values based on literature/my experience for rings targeting ~50Gbaud.

Future work would include looking at ways to speedup the ring and adding examples of PAM-4 for a ring modulator.

Summary by Sourcery

Adds a ring modulator device with accurate models of the time dynamics and optical peaking of the ring. Includes parameters for rings targeting ~50Gbaud.

New Features:

• Introduces a RingModulator class that models the time-domain and frequency-domain response of an optical ring resonator to optical and voltage inputs.
• Adds functionality to process input waveforms through the resonator, accounting for wavelength offset and voltage modulation.
• Implements an RC filter for the voltage input to model electrical effects.
• Provides methods to calculate and plot the frequency response of the resonator.
• Includes properties to calculate key ring resonator parameters such as FSR, finesse, FWHM, quality factor, and photon lifetime.