chore: add codeowners

Author: yaugenst-flex

.github/CODEOWNERS

@@ -0,0 +1,8 @@
+.github/workflows/ @daquinteroflex
+tidy3d/components/autograd/ @yaugenst-flex @tylerflex @groberts-flex
+tidy3d/components/dispersion_fitter.py @caseyflex
+tidy3d/components/eme/ @caseyflex
+tidy3d/components/microwave/ @dmarek-flex @weiliangjin2021
+tidy3d/components/spice/ @marc-flex
+tidy3d/components/tcad/ @marc-flex
+tidy3d/config/ @yaugenst-flex