Warn adduser changes, undeprecate --auth-type, but warn for some values

[fritzy]

• feat: notify on adduser of upcoming cmds, login and register
• feat: deprecate --auth-type=sso/saml/oauth, undeprecate --auth-type

[fritzy]

Please don't squash.

[npm-cli-bot]

found 1 benchmarks with statistically significant performance regressions

• app-large: no-clean

timing results

app-large	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit
npm@8	41.723 ±1.47	20.673 ±0.31	17.245 ±0.15	20.065 ±2.11	2.837 ±0.05	3.060 ±0.03	2.500 ±0.10	11.391 ±0.03	2.260 ±0.01	3.593 ±0.02
#5149	41.297 ±0.84	19.689 ±0.29	17.774 ±0.06	21.202 ±1.03	3.110 ±0.04	3.103 ±0.04	2.489 ±0.03	12.216 ±0.14	2.601 ±0.05	3.781 ±0.21

app-medium	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit
npm@8	29.568 ±0.31	14.757 ±0.04	12.968 ±0.00	13.440 ±0.26	2.758 ±0.14	2.811 ±0.03	2.498 ±0.03	8.674 ±0.04	2.359 ±0.02	3.396 ±0.30
#5149	31.707 ±0.28	15.169 ±0.02	13.290 ±0.20	14.303 ±0.18	2.853 ±0.05	2.806 ±0.07	2.447 ±0.01	9.229 ±0.12	2.523 ±0.10	3.369 ±0.01

[wraithgar]

Approved w/ one tiny suggestion you can ignore if you want.