feat(@schematics/angular): add generation for resolvers

[Jefiozie]

This will add the resolvers as an option to generate.
You can use it by ng g r <name> or ng generate resolver <name>

closes: #17569

[Jefiozie]

Just referencing @alan-agius4 or @clydin for reviewing 😄

[alan-agius4]

Thanks for this, one small NIT.

[Jefiozie]

Will make these changes as soon as i have some time.

[Jefiozie]

Hey @alan-agius4, I have changed your comments, I think it is good to do a quick review again. Thanks for your comments.

[alan-agius4]

Thanks for your contribution @Jefiozie.

[Jefiozie]

Thank you, hope to do some more contributions.

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