[RSDK-7267] Board cleanup part 1: analogs can be written to

[penguinland]

• AnalogReader is now just Analog. Similarly, analog_reader_by_name is just analog_by_name, etc.
• The Analog abstract class can now .write() in addition to .read().
• (The underlying RPCs are unchanged: it's still a WriteAnalog RPC on the board. but SDK users don't interact directly with the RPCs.)

In an upcoming PR, I'll have more board cleanup to stream digital interrupts. but that's separate enough to warrant a separate PR.

[github-actions]

Warning your change may break code samples. If your change modifies any of the following functions please contact @viamrobotics/fleet-management. Thanks!

component	function
base	is_moving
board	gpio_pin_by_name
camera	get_image
encoder	get_position
motor	is_moving
sensor	get_readings
servo	get_position
arm	get_end_position
gantry	get_lengths
gripper	is_moving
movement_sensor	get_linear_acceleration
input_controller	get_controls
audio	get_properties
pose_tracker	get_poses
power_sensor	get_power
motion	get_pose
vision	get_classifications_from_camera

[penguinland]

Don't worry, github-actions bot. I didn't touch board.gpio_pin_by_name.

[penguinland]

This paragraph is unrelated to my main change, but also has nothing to do with the function it's documenting. Reading an analog pin doesn't involve PWM, and I suspect this "documentation" was added via a copy-and-paste mistake.

[penguinland]

I've needed to rerun the tests several times because they time out after 1 minute, and only 95ish% of the tests finish in a minute. Is this expected? I'm unsure if I've somehow made the tests much slower than normal, or the timeout threshold ought to be raised. With enough reruns, the tests can pass within the time limit...

[stuqdog]

One minor thing (no need to re-request review) otherwise lgtm!

[penguinland]

In an upcoming PR, I'll have more board cleanup to stream digital interrupts.

Surprise, no I won't! Olivia already did that 2 weeks ago.