github: Move to a typed graphql client instead of handrolled queries

[jerry-skydio]

Download and checkin github's schema, then create a codegen client with
ariadne-codegen. This significantly improves the readability of the
github forge code.

[jerry-skydio]

Reviews in this chain:
└#249 forge: Genericize github handling into a forge abstraction
　└#250 test: Expand upload tests with fake_forge
　　└#251 github: Move to a typed graphql client instead of handrolled queries

[jerry-skydio]

#	head	base	diff	date	summary
0	becb9eec	48d65d5d	diff	May 20 12:37 PM	41 files changed, 66813 insertions(+), 614 deletions(-)
1	975373bf	48d65d5d	diff	May 20 12:43 PM	3 files changed, 59 insertions(+), 8 deletions(-)
2	1ff126dc	48d65d5d	diff	May 20 12:47 PM	4 files changed, 27 insertions(+), 53 deletions(-)
3	7a5e78b4	48d65d5d	diff	May 20 13:06 PM	3 files changed, 723 insertions(+), 422 deletions(-)