feat: general codebase improvements

[csatib02]

Overview

• Removed allow-leading-space from golangci.yaml since it was removed: missing config allow-leading-space for nolintlint golangci/golangci-lint#3063 (comment)
• Also updated nix.flake to use latest golangci-lint
• Propagated context to lower level packages, but found some issues with the sync command. All is covered in this issue.
• Changed fmt.Errorf() calls to errors.New() where no arguments were passed.
• Separated the code with a bunch of new line characters, to make blocks inside of functions more readable.
• Converted tests to a table-driven format.
• Implemented initStore() function in sync.go to collect all init steps of a provider.
• Removed unnecessary variables.
• Regenerated the images...
• Created 2 other issues: Enable Auditing #203 Use Vault-SDK Bank-Vaults packages for all types of interaction with Vault #204

Notes for reviewer

[ramizpolic]

lgtm, thanks @csatib02!