Improve/rationalise sizing of musical symbols within text

Depending on the item type, text/text-based items (including text lines) use either the musical text font of the musical symbols font when SMuFL symbols are used within them.

Ottavas, harp pedal diagrams (not text diagrams), tuplets, pedal lines, dynamics and string tunings use the musical symbols font; all other types use the musical text font.

Currently, all text styles have a 'Musical symbols scale' setting (in Style -> Text styles). this is non-functional for any types except those just listed, so this should be removed (see #28858). Several, though not all, of the types for which this is relevant also have a Scale setting in Properties.

As of #29890, other text types have a 'Symbol size' setting in Properties (first introduced for jumps/markers in #28377), but no accessible global setting.

To make this consistent:

• Each text item type should have, in Style, a score-wide setting for either its symbol scale (in %, for those types using the musical symbols font) or its symbol size (in pt, for other types)
• Each text item type should have the corresponding symbol scale or symbol size setting available in Properties (with the ability to reset it to the score-wide default, or set as a new default)

There is the ongoing matter of reorganising text styles (and the entire style dialog generally). I'm increasingly of the opinion that text styles should be kept abstract (in theory, any style could be used for any text-based item) and that any behaviour that pertains to the type in question should be on its respective page in the dialog, but this all needs design discussion. (By 'abstract' I mean that they just define a specific styling for text, but that they are not tied to a specific item type. Some item types now let you select which text style you wish to use for them, e.g. fret numbers and measure numbers, and while each has a default style with a corresponding name, these are not inherently tied to the type - they could be used for other types, or you could create your own types in order to switch between different ones easily, etc.)