Choose the TOTP format to be generated

After reading some old issues, I realized the situation is more complex, so here is my revision:

**Is your feature request related to a problem? Please describe.**
In official KeePass using the KeeTrayTOTP plugin, the totp information is stored in two separate fields (seed and specifications), and the two field names can be customized in the plugin settings. Keepass2Android use this format and provide the same settings to set custom field names as to KeeTrayTOTP.

KeePassXC and KeePassDX do not recognize the KeeTrayTOTP format, so as other implementations that do support two fields format but lack the support of field name customization.

**Describe the solution you'd like**
Provide field name customization in the settings, and read like KeeTrayTOTP when those fields are detected?
Plus some settings to let the user choose what format to use by default when adding totp information.

Start by locating the existing TOTP field handling and settings in the Android application, then compare them with the KeeTrayTOTP two-field format described here. Done means supporting customizable field names for detected fields and a setting to choose the default format when adding TOTP information.

Written by the indexing model from the issue text.