add file-types flag

[gurukiran07]

closes #174

Added file-types flag to validator. file-types and exclude-file-types are mutually exclusive. if file-type is set then builds a list of files that can be excluded and sets that value to exclude-file-types flag.

Some rudimentary tests:

with --file-types=yaml

with --exclude-file-types and --file-types

[gurukiran07]

1. Add unit tests for your changes
2. Fix issues identified in failed jobs: golangci-lint and goreportcard

Done. Pipeline's green. Let me know if there's anything else I need to do. @kehoecj

[kehoecj]

@gurukiran07 Please resolve conflicts then I think you're good to go

[gurukiran07]

@gurukiran07 Please resolve conflicts then I think you're good to go

Done.

[gurukiran07]

Will make the requested changes when I get some time today.

[kehoecj]

@gurukiran07 Please resolve conflicts and I'll work on getting this merged today

[gurukiran07]

@gurukiran07 Please resolve conflicts and I'll work on getting this merged today

@kehoecj Done. Fixed the conflicts.

Some basic testing:

• with both exclude-file-types and file-types

• with just file-types

• with just exclude-file-types

[gurukiran07]

Do you think you could add the tests I'm talking about here

#192 (comment)

Yeah I can. Will work on it when I get some time.

[kehoecj]

@gurukiran07 Please resolve conflicts

[kehoecj]

@gurukiran07 We probably want this to also be mutually exclusive with the new globbing functionality

[kehoecj]

@gurukiran07 I would like to get this merged in. Can you please take a look at several outstanding comments?