fix(lint): explicitly configures ireturn exceptions

Description

Instead of using //nolint:ireturn the linter allows the use of generic return types through the global config (on top of the listed defaults which now have been explicitly set).

This approach also eliminates a recurring issue where nolintlint reports the directive above as not used by the defined linter.

On top of that, we have --fix flag enabled for golangci-lint runner. This results in the removal of these comments as nolintlint tries to auto fix.

As a consequence the subsequent run of make lint yields errors for previously disabled linters and the cycle continues :)

[!IMPORTANT] This behaviour has also been observed for other linters.

As part of this work, the declarations of kustomize plugin constructor funcs has been reworked to return struct pointers instead. The reason for this is that in our feature branch, we rely on kustomize plugins and want to iterate over a slice of resmap.Transfomers but these functions cannot be used in the current form because structs returned have pointer receivers. From the current functionality standpoint (on the incubation branch) this change is harmless.

How Has This Been Tested?

make

Screenshot or short clip

Merge criteria

[x] You have read the contributors guide.
[x] Commit messages are meaningful - have a clear and concise summary and detailed explanation of what was changed and why.
[x] Pull Request contains a description of the solution, a link to the JIRA issue, and to any dependent or related Pull Request.
[ ] ~Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).~
[x] The developer has manually tested the changes and verified that the changes work

opendatahub-io / opendatahub-operator