Added capability of migrating wallet through the node.js wrapper

[bobozaur]

Exposes the wallet migration functionality in the Node.js wrapper

[Patrik-Stas]

This is not yet usable in practice - libvcx, unlike aries-vcx, is singletonish about everything - there's concept of "main wallet", "main pool", "main agency client" etc.

While technically you have access to wallet handle (open_as_main_wallet returns it), there's no place we need nodejs consumers to actually work with (any) handles. So to stay consistent, I would rather prefer to have something like "migrate_main_wallet(destWalletHandle)" with expectation that the user must call open_as_main_wallet first, and that's gonna be the source wallet.

The problem with migrate_main_wallet(destWalletHandle) however is that you don't have any way to get the destWalletHandle, because of singletonish nature of libvcx.
So a solution for that would be to have interface migrate_main_wallet(wallet_config, wallet_credentials) on vcx-napi-rs level, and also libvcx_core level, then proceed and within that function open the destination wallet and provide the handle to the migrator itself.

It would be good to include simple unit test - create wallet and migrate it (even if there's no records) just to make sure that the basic flow works and the API can be worked with.

[codecov-commenter]

Codecov Report

Merging #895 (63db665) into main (d16b933) will increase coverage by 0.00%.
The diff coverage is 0.00%.

❗ Current head 63db665 differs from pull request most recent head 76a8bdb. Consider uploading reports for the commit 76a8bdb to get more accurate results

@@           Coverage Diff           @@
##             main     #895   +/-   ##
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  Coverage   43.36%   43.36%           
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  Files         438      438           
  Lines       34778    34781    +3     
  Branches     7581     7591   +10     
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+ Hits        15080    15082    +2     
- Misses      15234    15237    +3     
+ Partials     4464     4462    -2     

Flag	Coverage Δ
unittests-aries-vcx	43.36% <0.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
libvdrtools/indy-api-types/src/lib.rs	50.00% <0.00%> (-30.00%)	⬇️

... and 2 files with indirect coverage changes