Stop returning Lua tables with 0-indexing

[YoshiRulz]

These are non-idiomatic and annoying to work with (though IMO the normal 1-indexed tables are also annoying).
Switching a function's indexing is a breaking change, so we should plan to change them all at once. The candidates are:

• client.getavailabletools()
• comm.mmfReadBytes(string, int)
• event.availableScopes()
• memory.getmemorydomainlist()
• (deprecated) memory.readbyterange(long, int, string?)/mainmemory.readbyterange(long, int)
• movie.getcomments()/movie.getsubtitles()
• tastudio.getbranches()/tastudio.getselection()

[SuuperW]

Will need to add functions that take a 0-based index as an argument too. Idk if any exist, but I saw the update in #4335.

Also if we do this, can we please also standardize the function names? E.g. make them all use underscores, client.getavailabletools -> client.get_available_tools.