fix: don't overwrite config keys unless they've really changed

[wraithgar]

• fix: move to private attributes where possible
• fix: save raw data to file, not parsed data

[wraithgar]

npm tests fail w/ this, need to fix that first.

[wraithgar]

👍 on the last mile fix, thanks!

[npm-cli-bot]

no statistically significant performance changes detected

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	show-version	run-script
npm@9	38.945 ±1.60	20.401 ±0.16	19.604 ±0.21	22.714 ±0.59	3.595 ±0.05	3.600 ±0.04	2.829 ±0.05	13.421 ±0.10	2.803 ±0.03	4.120 ±0.13	0.629 ±0.04	0.647 ±0.06
#6328	37.857 ±2.94	20.824 ±0.28	19.867 ±0.29	22.741 ±0.72	3.686 ±0.02	3.790 ±0.03	3.090 ±0.01	13.565 ±0.06	2.793 ±0.02	4.319 ±0.36	0.645 ±0.03	0.616 ±0.00

app-medium	clean	lock-only	cache-only	cache-only peer-deps	modules-only	no-lock	no-cache	no-modules	no-clean	no-clean audit	show-version	run-script
npm@9	27.852 ±0.43	15.238 ±0.11	14.980 ±0.04	15.842 ±0.22	3.248 ±0.07	3.245 ±0.04	2.807 ±0.01	10.170 ±0.17	2.689 ±0.05	3.663 ±0.02	0.613 ±0.00	0.618 ±0.01
#6328	27.570 ±0.95	15.464 ±0.12	14.993 ±0.16	16.123 ±0.26	3.294 ±0.10	3.339 ±0.07	2.860 ±0.08	10.312 ±0.16	2.675 ±0.02	3.720 ±0.06	0.598 ±0.00	0.616 ±0.01