added save_utm_parameters flag to Tito components

[danielfmiranda]

Description

Related PRs/issues: #12035

This pull request implements enhancements to the <tito-button> elements within the tito_widget_block.html and tickets_block.htmltemplates.

It introduces the save-metadata-parameters="utm_*" flag, to enable these Tito elements to capture UTM parameters, as outlined in the documentation. (see "UTM parameters" underneath the "Prefill section").

Screenshots

Testing TitoWidgetBlock UTM tracking

1. Visiting the page with UTM parameters (TitoWidgetBlock is the button that says "test")

2. Tito dashboard after signing up using Tito Widget Block (note that the donation kept track of all UTM params)

Testing TicketsBlock UTM tracking

1. Visiting the page with UTM parameters (tickets block is the grey square mentioning tickets for 55 euro)

2. Tito dashboard after signing up using TicketBlock (note that the donation kept track of all UTM params)

┆Issue is synchronized with this Jira Story

[robdivincenzo]

LGTM! Thanks @danielfmiranda 👍