Feature: Filter engine build menu by name and NewGRF extra text

[2TallTyler]

Motivation / Problem

In #8984, @perezdidac started the work of adding a text filter to the build vehicle menu, but hasn't been touched in 10 months. Let's finish it.

Description

Implements #8984 with a change to put the editbox below the other lines:

I added the ability to search NewGRF extra text, which is often used to describe a vehicle's role:

It also works with the vehicle name callback added in #10399 (there's an example trainset in that PR):

If variants are used (unreleased Iron Horse 2 in this screenshot), a subvariant that meets the filter, nested inside a parent does not, will show up underneath its greyed-out parent variant, collapsed by default.

Closes #8984.

Limitations

I tried swapping the cargo filter dropdown and the editbox in the GUI, and the cargo filter all by itself looked much more wrong than a full-width textbox (which we have elsewhere in the GUI, including the object menu).

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, gs_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker

[audigex]

Additional Text length testing - appears to be 2046 characters

[audigex]

It would be nice if the nested results were expanded down the tree to the search result, I think? Not a huge issue, but that would seem more intuitive to me

[rubidium42]

Looks okay to me.