Fix IAM policies setup for functions with custom name

[medikoo]

Fixes #6236

It appears that #6212 handled only function names as resolved when no name is provided.
This patch ensure that proper polices are also created for functions with custom name

Is this ready for review?: YES
Is it a breaking change?: NO

[weeniearms]

@medikoo It'd also be good to extract these policies into managed policies to avoid #6212 from reoccurring when someone has a lot of functions with custom names. There is a default limit (1500) for customer managed policies, but that's a limit that can be changed unlike the user/role/group combined inline policy size.

[medikoo]

It'd also be good to extract these policies into managed policies

Yes, it probably can be next step (it also might have been discussed already). Still here we're just fixing the improvement made for functions with default names -> #6236.

[eahefnawy]

Don't see any issues with this fix. LG2M. 👍