  We report detections of the [OIII]$\lambda$4364 auroral emission line for 16
galaxies at z=2.1-8.7, measured from JWST/NIRSpec observations obtained as part
of the Cosmic Evolution Early Release Science (CEERS) survey program. We
combine this CEERS sample with 9 objects from the literature at z=4-9 with
auroral-line detections from JWST/NIRSpec and 21 galaxies at z=1.4-3.7 with
auroral-line detections from ground-based spectroscopy. We derive electron
temperature T_e and direct-method oxygen abundances for the combined sample of
46 star-forming galaxies at z=1.4-8.7. We use these measurements to construct
the first high-redshift empirical T_e-based metallicity calibrations for the
strong-line ratios [OIII]/H$\beta$, [OII]/H$\beta$,
R23=([OIII]+[OII])/H$\beta$, [OIII]/[OII], and [NeIII]/[OII]. These new
calibrations are valid over 12+log(O/H)=7.0-8.4 and can be applied to samples
of star-forming galaxies at z=2-9, leading to an improvement in the accuracy of
metallicity determinations at Cosmic Noon and in the Epoch of Reionization. The
high-redshift strong-line relations are offset from calibrations based on
typical $z\sim0$ galaxies or HII regions, reflecting the known evolution of
ionization conditions between $z\sim0$ and $z\sim2$. Deep spectroscopic
programs with JWST/NIRSpec promise to improve statistics at the low and high
ends of the metallicity range covered by the current sample, as well as improve
the detection rate of [NII]$\lambda$6585 to allow the future assessment of
N-based indicators. These new high-redshift calibrations will enable accurate
characterizations of metallicity scaling relations at high redshift, improving
our understanding of feedback and baryon cycling in the early universe.
