[ADD] l10n_ec_reports_ats: Ecuadorian ATS Report (SRI)

The Simplified Transactional Annex (Anexo Transaccional Simplificado - ATS)

Developed in collaboration with the Trescloud team

[General description]
- Report generated in xml to be uploaded to the DIMM software of the SRI (Servicio de Rentas Internas) in Ecuador.
- Added button action to generate the ATS report in XML, in Accounting > Reports > Tax Report.
- The ATS is generated per month.
- Non-blocking error notifications in the ATS XML generation process

[Purchase Document Reports]
- Local and foreign purchase documents grouped by partner and tax support.
- All pre-printed and electronic purchasing documents are included.
- Total amounts of profit and VAT in withholding taxes for the purchase documents to be declared in the selected period.
- Report pre-printed and electronic withholdings for each purchase document, if it was generated for that purchase document and the withhold date is in the search period.

[Report sales documents]
- Pre-printed and electronic sales documents grouped by partner.

[Report void documents]
- Pre-printed and electronic documents canceled in the selected period.
- Canceled sales, purchase and withholding documents are included.

Task: 3303501
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[FIX] l10n_ec_reports: Fix manifest icons options

- Add 'countries' option in the module manifest
- Delete static files. This way of displaying icons is deprecated.

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[IMP] l10n_ec_edi: Cases to show and edit EC authorization number

- Hide EC authorization number for not EC documents, documents without a document type and if the document is not a withhold
- Allow editing of the authorization number for EC pre-printed and manual documents
- Do not allow the editing of electronic documents