Contacts - Add support for VCF Version 4.0 for import and export .vcf file

What?

Evaluate how we could support vcf version 4.0 within /e/OS (/e/OS Contacts app).

How?

1. Create the new page under https://gitlab.e.foundation/internal/wiki/-/wikis/studies
2. and add the link at https://gitlab.e.foundation/internal/wiki/-/wikis/studies
3. Fill the following template, and add it on the page you created previously

# Study

## 1. The problem to solve

By default /e/OS Contacts app does not support importing contact informations from VCF 4.0 format vCards. And contact info exporting is by default only in VCF 2.1 format, There's no way to change this.

## 2. The approaches

1. Allowing users to import vCards in VCF 2.1 to 4.0 and adding an option to change default export format of vCard to VCF 2.1, 3.0 or 4.0. And also set default vCard export version to 4.0 by default.
2. Same as 1, but default export version VCF 3.0.
3. Allow users to import contacts from vCards versions 2.1 to 4.0 and allow export only in VCF 4.0.

## 3. The recommendation

The first approach is more suitable for this, which allows users to change the default one and exports by default in VCF 4.0. 

## 4. The choice

Allowing users to import vCards in VCF 2.1/3.0/4.0 and adding an option to change default export format of vCard to VCF 2.1/3.0/4.0. And also set default vCard export version to 4.0 by default.

4. Discuss the recommendation with at least tech lead and manager, before aligning on the choice

Why?

Our contact app supports VCF file version 2.1 while most services support version 4.0. When a user tries to import contacts as a vcf file, it doesn't work. The version 4.0 would offer a better compatibility with other platforms.

Most likely solves:

• #501 (closed)
• #972 (closed)
• #5480 (closed)

/cc @jonathanklee @rhunault @aude.m