refactor(parameters): types in BaseProvider + added getMultiple alias to SecretsProvider

[dreamorosi]

Description of your changes

This PR removes the method overrides from the get and getMultiple methods in the BaseProvider so that children classes can set their own types on these methods. See #1213 for full details.

How to verify this change

See existing checks under the PR.

Related issues, RFCs

Issue number: #1213

PR status

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

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding changes to the examples
• My changes generate no new warnings
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published
• The PR title follows the conventional commit semantics

Breaking change checklist

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.