fix: usr: Use named Service Parameter Keys (SvcParamKeys) by default

When converting SVCB records to text representation `named` now uses named
`SvcParamKeys` values unless backward-compatible mode is activated,
in which case the values which were not defined initially in
RFC9460 and were added later (see [1]) are converted to opaque
"keyNNNN" syntax, like, for example, "key7" instead of "dohpath".

Also a new `+[no]svcparamkeycompat` option is implemented for `dig`,
which enables the backward-compatible mode and uses the opaque
syntax, if required for interoperability with other software or
scripts. By default, the compatibility mode is disabled.

[1] https://www.iana.org/assignments/dns-svcb/dns-svcb.xhtml

Closes #5156

Merge branch '5156-svcparamkey-use-named-keys-by-default' into 'main'

See merge request isc-projects/bind9!10085