tests: added tests for VaultsSecretsWriteFile

chore: updated secrets remove to properly operate on multiple paths

chore: working on proper error wrapping for unexpected errors

chore: added comments and cleaned up VaultOps

chore: split vaultsSecretsGet and its tests

chore: dealing with an edge case when error cannot be serialised

chore: cleaned up files

chore: added intelligent error message synthesis

deps: updated version of @matrixai/rpc

fix: handle attempt to remove vault root

Wrapping `VaultOps` errors in `ErrorPolykey` errors and updating tests