Add upload tests

[jerry-skydio]

This tests subsets of functionality that don't touch github (by passing
dry-run). More work is needed to expand tests to that which touches
github.

[jerry-skydio]

Reviews in this chain:
└#232 Add upload tests
　└#236 upload: Don't re-add assignees/reviewers that were removed
　　└#238 upload: Add pr body source argument

[jerry-skydio]

#	head	base	diff	date	summary
0	9df16174	d80fc364	diff	Apr 20 11:19 AM	1 file changed, 978 insertions(+)
1	7c471e21	d80fc364	diff	Apr 20 12:58 PM	1 file changed, 10 insertions(+), 30 deletions(-)
2	a4a7a25e	d80fc364	diff	Apr 21 16:46 PM	1 file changed, 61 insertions(+), 218 deletions(-)
3	b16eda05	d80fc364	diff	Apr 21 16:47 PM	1 file changed, 19 insertions(+), 57 deletions(-)
4	37b50134	4c8aee30	rebase	Apr 21 17:07 PM	0 files changed
5	18263bc1	52017799	rebase	Apr 21 17:07 PM	0 files changed
6	f10037ff	9aec3314	rebase	Apr 21 17:11 PM	0 files changed
7	67c4ea72	674e434d	rebase	Apr 22 19:58 PM	0 files changed
8	2758976e	4c8aee30	rebase	Apr 22 20:04 PM	0 files changed
9	67c4ea72	674e434d	rebase	Apr 22 20:13 PM	0 files changed
10	9b12d3a2	a969bc14	diff	Apr 23 12:38 PM	1 file changed, 1 insertion(+), 1 deletion(-)
11	77c08739	79f0363b	diff	Apr 23 15:01 PM	0 files changed
12	8ef07d58	8b92128e	rebase	Apr 28 12:17 PM	0 files changed
13	9cf38dc9	e6a4cc88	rebase	Apr 28 12:19 PM	0 files changed
14	f7c9d0de	d2421ad8	diff	Apr 28 12:20 PM	0 files changed