feat: fully support Basic Authorization header at token request #4019

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	32s
checks / test (3.11, highest, ubuntu-latest)	48s
checks / test (3.11, lowest-direct, ubuntu-latest)	46s
checks / test (3.10, highest, windows-latest)	2m 41s
checks / test (3.10, highest, ubuntu-latest)	44s
checks / test (3.11, lowest-direct, windows-latest)	2m 27s
checks / test (3.10, lowest-direct, windows-latest)	3m 10s
checks / test (3.13, lowest-direct, windows-latest)	2m 59s
checks / test (3.10, lowest-direct, ubuntu-latest)	49s
checks / test (3.14, highest, windows-latest)	2m 17s
checks / test (3.11, highest, windows-latest)	2m 47s
checks / test (3.12, highest, ubuntu-latest)	50s
checks / test (3.13, highest, ubuntu-latest)	45s
checks / test (3.14, lowest-direct, windows-latest)	2m 8s
checks / test (3.13, highest, windows-latest)	2m 44s
checks / test (3.12, highest, windows-latest)	3m 57s
checks / test (3.13, lowest-direct, ubuntu-latest)	42s
checks / test (3.12, lowest-direct, ubuntu-latest)	50s
checks / test (3.12, lowest-direct, windows-latest)	3m 11s
checks / test (3.14, highest, ubuntu-latest)	1m 12s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 10s
	37m 40s

Provide feedback