Fix SAPI4 prosody regressions (#15502)
Fixes #15500
Follow up of #15271
Summary of the issue:
Some SAPI4 synthesizers reset all their prosody values to their defaults when they come across prosody in a sequence.
Description of user facing changes
Capital pitch changes no longer cause some SAPI4 voices to reset their rate and volume.
Description of development approach
When a sequence contains any prosody command, for the other prosody commands supported by the synth, we add commands to set them to the currently configured value.
