Avoids unnecessary atomic increments and decrements.

General: Make use of std::nullopt where applicable

Allows some implementations to avoid completely zeroing out the internal
buffer of the optional, and instead only set the validity byte within
the structure.

This also makes it consistent how we return empty optionals.

ips_layer: Eliminate a redundant copy in Parse()

Prevents unnecessary copying of the line being parsed.

submission_package: Account for multi-content NSPs

renderer_opengl: Remove emulated mailbox presentation

hid: Implement Get/SetNpadHandheldActivationMode

Emulated mailbox presentation was causing performance issues on
Nvidia's OpenGL driver. Remove it.

Test: Decrease pad_update_ns

fermi_2d: Make use of designated initializers

Same behavior, less repetition. We can also ensure all members of Config
are initialized.

- Used in Clubhouse Games: 51 Worldwide Classics

configure_input_player: Fixes motion mapping using ConfigureButtonClick

configure_input_player: Re-add "Clear" context menu option

am: Stub GetPreviousProgramIndex

- Used in Super Mario 3D All-Stars

The context menu was removed in Mjölnir Part 1 as part of the input rewrite as we were unaware of it's usage statistics.
However, as this was the only way to clear the inputs of individual buttons, this PR will re-add it back in.

Previously we assumed a submission package can only contain one Program NCA with a single TitleID.
However, Super Mario 3D All-Stars contains four Program NCAs, each with their unique TitleIDs.
This accounts for the existence of multi-content games such as this one.
- Fixes booting Super Mario 3D All-Stars from the games list.

arm_dynarmic_cp15: Initialize member variables

service/sm: Eliminate dependency on the global system instance

service: Remove unused funcation

command_generator/nfp: Eliminate unnecessary copies

decoder/texture: Eliminate narrowing conversion in GetTldCode()

decode/image: Eliminate switch fallthrough in DecodeImage()

hid/configuration: Implement motion controls to HID

Fortunately this didn't result in any issues, given the block that code
was falling through to would immediately break.

The assignment was previously truncating a u64 value to a bool.

In a lot of cases, we can make use of const references rather than
non-const references.

While we're in the area we can silence some truncation and sign
conversion warnings.

GetAmiiboBuffer() returns by const reference, so we can use a reference
instead of taking the returned buffer by value.

Ensures that the member variables are always initialized to a
deterministic value on creation.

control_metadata: Resolve typo in Portuguese language name

This isn't used anywhere, so this is a trivial fix.

This is now completely unused, so it can be removed.

We can check the end of the string first for null-termination, rather
than the beginning of the string.

gc_adapter: Disable MSVC nonstandard extension warning on libusb.h

video_core: Enforce -Werror=switch