Adjusted examples to Amaranth 0.4.0+

[littlelailo]

In Amaranth 0.4.0 the Pin instance can no longer simply be cast to a Value,
instead you have to specify the input/output direction when accessing it.

I changed the examples in two commits to work on newer version of Amaranth (tested against 0.5.3).
The first commit updates blink and uart, which I both flashed and tested (well it blinks and loopback is working).
The second commit fixes the remaining examples.
There I was only able to test flashing them but not if they work as I don't have the accessories.

The pdm_fade_gamma example unfortunately doesn't build for me at all so I was unable to fix that:

/<censored>/icebreaker-amaranth-examples/icebreaker/pdm_fade_gamma/gamma_pdm.py:112: DeprecationWarning: `amaranth.hdl.Memory` is deprecated, use `amaranth.lib.memory.Memory` instead
  self.gamma_table = Memory(width=out_width, depth=2**in_width, init=gamma_init)
ERROR: Found error in internal cell \top.cnt.$13 ($memrd_v2) at kernel/rtlil.cc:1579:
  attribute \src "/<censored>/icebreaker-amaranth-examples/icebreaker/pdm_fade_gamma/gamma_pdm.py:122"
  cell $memrd_v2 $13
    parameter \CLK_POLARITY 1
    parameter \CLK_ENABLE 1
    parameter \CE_OVER_SRST 0
    parameter \INIT_VALUE 16'xxxxxxxxxxxxxxxx
    parameter \SRST_VALUE 16'xxxxxxxxxxxxxxxx
    parameter \ARST_VALUE 16'xxxxxxxxxxxxxxxx
    parameter \COLLISION_X_MASK 0'
    parameter \TRANSPARENCY_MASK 0'
    parameter \WIDTH 16
    parameter \ABITS 8
    parameter \MEMID "\\gamma_rd_p"
    connect \CLK \clk
    connect \EN 1'1
    connect \SRST 1'0
    connect \ARST 1'0
    connect \DATA \pdm_level_gamma_n
    connect \ADDR $4 [7:0]
  end
Traceback (most recent call last):
  File "/<censored>/icebreaker-amaranth-examples/icebreaker/pdm_fade_gamma/gamma_pdm.py", line 189, in <module>
    plat.build(Top(gamma=args.g), do_program=True)
  File "/opt/homebrew/lib/python3.11/site-packages/amaranth/build/plat.py", line 103, in build
    products = plan.execute_local(build_dir)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/lib/python3.11/site-packages/amaranth/build/run.py", line 118, in execute_local
    subprocess.check_call(["sh", f"{self.script}.sh"],
  File "/opt/homebrew/Cellar/[email protected]/3.11.9_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/subprocess.py", line 413, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['sh', 'build_top.sh']' returned non-zero exit status 1.