Initialize AccountsModule behind FF_ACCOUNTS

[hectorgomezv]

Summary

AccountsDatasource was added in #1654

This PR initializes the class dependency chain (AccountsModule -> AccountsRepository -> AccountsDatasource) in AppModule, when FF_ACCOUNTS is enabled in the configuration.

Note: as a side effect of this change, /migrations/00001_accounts/index.sql will be applied if FF_ACCOUNTS is enabled.

Changes

• Adds AccountsModule and AccountsRepository (along with its interface).
• Imports AccountsDatasourceModule into AccountsRepositoryModule.

[coveralls]

Pull Request Test Coverage Report for Build 9520451734

Details

• 11 of 11 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 92.326%

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Totals
Change from base Build 9518177005:	0.1%
Covered Lines:	6893
Relevant Lines:	7181

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💛 - Coveralls