feat: expose cache manager alias provider Cache class with same as the interface from cache-manager

[micalevisk]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: closes #253

What is the new behavior?

1. no need to use @Inject(CACHE_MANAGER) anymore
2. no need to import Cache from another package. Always use the @nestjs/cache-manager one

Does this PR introduce a breaking change?

• Yes
• No

Other information

[kamilmysliwiec]

lgtm