Add built-in xstrs for SCP-added controls

[MjnMixael]

These controls, added by SCP were never given XSTRs for localization. This PR adds them. Fixes #4611

• 1799, Glide When Pressed
• 1800, Toggle Gliding
• 1801, Cycle Primary Weapon Firing Rate
• 1802, Top-Down View
• 1803, Target Padlock View
• 1804, Toggle Auto Pilot
• 1805, Cycle Nav Points
• 1806, Toggle HUD Drop Shadows

Note that built-in xstrs were required to be sequential and fit within a fixed sized array at the time that bug was reported. That is no longer the case and a deep dive to find unused xstr IDs is not necessary anymore.

[TRBlount]

Putting this on hold until review for #5622 is covered.

[MjnMixael]

Putting this on hold until review for #5622 is covered.

Already altered taking that PR into account

[TRBlount]

With the final version of #5622 ready, the IDs need to be shifted back so 1774 is occupied. XSTR_SIZE can be left as is here.

[MjnMixael]

With the final version of #5622 ready, the IDs need to be shifted back so 1774 is occupied. XSTR_SIZE can be left as is here.

done