Feature/lit 3140 make pkp base a private instance variable in pkp

[FedericoAmura]

Description

This PR cleans PKPBase authContext and its ex-extending clases PKPEthersWallet, PKPCosmosWallet and PKPSuiWallet. Including changes:

• Removed extension from PKPBase, those classes now implement a shared interface and have a more restricted public interface
• Make litNodeClient a required param in PKP wallets and remove fields to create it, delegating that responsibility to user
• Removed redundant litNodeClient instance inside authContext
• Made PKPBase final (with a private constructor, there is no final in TS)
• Updated PKPClient due to these changes
• Fixed several type definitions
• Updated session sigs demo app to use all PKP wallet classes to test signing

This PR has BREAKING CHANGES due to changes in PKP*Wallet interfaces and removed things (WalletFactory)

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [x] Building and testing passing
• [x] New type validations SDK wide
• [x] session sigs demo updated to test signing using PKPEthersWallet, PKPCosmosWallet and PKPSuiWallet

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules