Include new `hb_subset` functions from hb 6+7

[papandreou]

Add new functions from harfbuzz 6 and 7 to the hb-subset.wasm build:

• hb_subset_input_keep_everything (6.0.0+)
• hb_subset_input_pin_axis_location (6.0.0+)
• hb_subset_input_pin_axis_to_default (6.0.0+)
• hb_subset_preprocess (7.0.0+)

I need these for https://github.com/papandreou/subset-font/pull/21 :hugs:

[papandreou]

Thanks, @khaledhosny! :bow:

Mind releasing a new version to the npm repo?

[khaledhosny]

Mind releasing a new version to the npm repo?

Done