Codechange: use StringParameters for remapping the NewGRF string control codes

[rubidium42]

Motivation / Problem

Passing a pointer and a size, instead of a reference to a structure that contains both.
And further down the line... to make it possible to change the underlying value type for the container.

Description

Replace the uint64 *argv, uint argv_size with StringParameters &parameters in the NewGRF remap function, and map the *argv =/argv[0] =/argv[1] = to the appropriate SetParam call.

Limitations

None.

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