PHILADELPHIA — On Thursday night, Opera Philadelphia opened its Festival O23 with the world premiere opera “10 Days in a Madhouse” from composer Rene Orth with a libretto by playwright Hannah Moscovitch. The festival, which runs through Oct. 1, also includes a main-stage production of Verdi’s “Simon Boccanegra” and tenor Karim Sulayman’s “Unholy Wars” as well as recitals at the Academy of Vocal Arts and Curtis Institute of Music.