In line with

    commit 0c2ebfad
    Date:   Tue Aug 6 16:02:55 2024 -0500

        Rename ATSPI_ROLE_PUSH_BUTTON to ATSPI_ROLE_BUTTON

, also rename `ATK_ROLE_PUSH_BUTTON` to `ATK_ROLE_BUTTON` and
leave `ATK_ROLE_PUSH_BUTTON` as an enum value with the
same name for compatibility reasons.

This e.g. ensures that both, libatspi and libatk use the
same name for the role, as that is generated based on
the name of the enum values.

This e.g. makes a sample program like

    #include <stdio.h>
    #include <atk/atk.h>
    #include <atspi/atspi.h>
    int main()
    {
        char* atspiRoleName = atspi_role_get_name(ATSPI_ROLE_BUTTON);
        printf("atspi name: %s\n", atspiRoleName);
        AtkRole atkRole = atk_role_for_name(atspiRoleName);
        printf("ATK role: %d, localized atk role: %s\n", atkRole, atk_role_get_localized_name(atkRole));

        atkRole = ATK_ROLE_PUSH_BUTTON;
        printf("ATK role: %d, localized atk role: %s\n", atkRole, atk_role_get_localized_name(atkRole));
        return 0;
    }

output

    atspi name: button
    ATK role: 42, localized atk role: button
    ATK role: 42, localized atk role: button

instead of

    atspi name: button
    ATK role: 0, localized atk role: invalid
    ATK role: 42, localized atk role: push button

The original real-world scenario where this mismatch
led to "invalid" being announced instead of a proper
role name was Orca. While applications probably shouldn't
mix role names from libatk and libatspi in the first place
(see Orca MR [1]), it still seems useful to keep this in
sync for the (push) button role.

[1] orca!226