config: Reorganize config code and add config command

[jerry-skydio]

In order to simplify the config code and provide people an easier way to edit their configs, move most of the writing logic out of the read() fn and into write() and set_value() functions. Running normal revup commands will no longer write to the config, instead only "revup config" will be able to write arbitrary config values. This means that users will no longer be required to enter an oauth for commands that don't talk to github, and if a command requires oauth, it will instead prompt users to run "revup config".

Topic: config

[jerry-skydio]

Reviews in this chain: └https://github.com/Skydio/revup/pull/83 config: Reorganize config code and add config command

[jerry-skydio]

#	head	base	diff	date	summary
0	dbcc9eb4	311ff10d	diff	Oct 28 21:40 PM	4 files changed, 153 insertions(+), 63 deletions(-)
1	144c0409	0e57937a	diff	Jan 11 15:04 PM	1 file changed, 13 insertions(+), 5 deletions(-)
2	094d2714	fa4e5a9a	diff	Mar 24 16:32 PM	0 files changed
3	a253541b	fa4e5a9a	diff	Apr 4 0:41 AM	3 files changed, 59 insertions(+), 36 deletions(-)
4	7f315c7c	fa4e5a9a	diff	Apr 4 0:59 AM	2 files changed, 32 insertions(+), 29 deletions(-)
5	baa17556	fa4e5a9a	diff	Apr 4 1:02 AM	1 file changed, 1 insertion(+), 2 deletions(-)
6	318db1e3	fa4e5a9a	diff	Apr 4 1:14 AM	3 files changed, 25 insertions(+), 27 deletions(-)
7	9afa72a6	fa4e5a9a	diff	Apr 4 1:20 AM	2 files changed, 3 insertions(+), 4 deletions(-)
8	077301ac	fa4e5a9a	diff	Apr 4 1:37 AM	1 file changed, 2 insertions(+), 2 deletions(-)
9	d727e2f1	fa4e5a9a	diff	Apr 4 3:02 AM	0 files changed
10	077301ac	fa4e5a9a	diff	Apr 4 7:31 AM	0 files changed
11	4ac7ae79	1a86af93	diff	Apr 4 19:01 PM	0 files changed
12	0f13b9f3	1a86af93	diff	Apr 4 19:02 PM	0 files changed