Enhancement Request: Grouped/Nested Roles

[ColinHalter]

When working with multiple orgs that have several accounts each, being able to condense certain roles into groups would be nice. I'm imagining something like this:

For the config side, I was thinking this syntax:

[profile Role1]
role_arn = arn:aws:iam::000000000000:role/AdminAccess
color = e6a160
region = us-east-1

[profile Role2]
group = Org1
role_arn = arn:aws:iam::000000000000:role/AdminAccess
color = 015589
region = us-east-2

[profile Role2.1]
group = Org1
role_arn = arn:aws:iam::000000000000:role/AdminAccess
color = d17a7a
region = us-east-1

[profile Role2.2]
group = Org1
role_arn = arn:aws:iam::000000000000:role/AdminAccess
region = us-east-1
color = e6a160

[profile Role3]
group = Org2
role_arn = arn:aws:iam::000000000000:role/AdminAccess
region = us-east-1
color = 60e677

[profile Role3.1]
group = Org2
role_arn = arn:aws:iam::000000000000:role/AdminAccess
color = 59afc5
region=us-east-1

[profile Role3.2]
group = Org2
role_arn = arn:aws:iam::000000000000:role/AdminAccess
color = 59afc5
region=us-east-1

[tilfin]

I have already made reference to the hierarchical menu in #198 .