Don't use <regex> to reduce binary size

[kkaefer]

We're only using <regex> in one instance, for removing access_token=* from URLs when putting them into the cache. However, <regex> adds quite a bit to the binary size; I'm measuring these size reductions:

• Android/arm-v7: 4,903,78 => 4,842,348 bytes, ~60KB reduction
• macOS/x86_64: 3,955,184 => 3,860,600 bytes, ~95KB reduction
• iOS/arm64: 3,012,356 => 2,961,728 bytes, ~50KB reduction

[mention-bot]

@kkaefer, thanks for your PR! By analyzing the history of the files in this pull request, we identified @mapsam, @jfirebaugh and @lucaswoj to be potential reviewers.

[mapsam]

This was very specifically added to ensure other parameters are preserved, and only access token is removed. This is important for style-optimized vector tile requests that may have a &style= parameter in the tile URL. If the tests continue to pass, 👍 from me.

[jfirebaugh]

I'm fine with this, although we'll likely eventually re-add this dependency for mapbox/mapbox-gl-style-spec#233 / mapbox/mapbox-gl-style-spec#321.

Don't forget to remove the #include <regex> too.

[kkaefer]

@mapsam yup, the code just looks for access_token fields and removes them, while preserving all others.

[mapsam]

Thanks @kkaefer!