[FR] sync multiple URLs support with keepassxc desktop app

### Checks

- [x] I have read the Wiki, searched the open issues, and still think this is a new feature.

### Explain the problem clearly and succinctly:

https://github.com/keepassxreboot/keepassxc/issues/11434

i have KeepassXC on desktop and keepassdx on android. They both support multiple URLs for one entry but in different ways (seems was never standartized)

- keepassxc: entry-details => browser-integration => additional-urls produses field/attribute KP2A_URL,KP2A_URL_1,KP2A_URL_x see page EntryDetails/Advanced
- keepassdx: looks simpler adds additional filed/attribute URL_1, URL_2, URL_x to entry

i better like way of keepassdx, and it seems to update desktop app is also simpler. Thanks.

for reference

- https://github.com/keepassxreboot/keepassxc/pull/3558
- https://github.com/keepassxreboot/keepassxc/issues/2356

### Describe the solution you'd like:

in addition to URL_1, URL_x fields pls support also KP2A_URL_1, KP2A_URL_x

Review the current handling of URL_1 and URL_x entry attributes, along with the referenced EntryDetails/Advanced behavior and linked KeePassXC discussions. Done means the app also supports KP2A_URL_1 and KP2A_URL_x fields for entries alongside the existing URL_1 and URL_x fields.

Written by the indexing model from the issue text.