* remove keyboard-level instances of `MIDI_ENABLE = no`

Command:

```
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e  '/^[ #]*MIDI_ENABLE[ \t]*=[ \t]*no/d' {} +
```

Co-Authored-By: Nick Brassel <nick@tzarc.org>

* fix case-sensitivity issues on MIDI_ENABLE

Change instances of `MIDI_ENABLE = YES` to `MIDI_ENABLE = yes`.

Command:

```
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e 's;MIDI_ENABLE[ \t]*=[ \t]*[Yy][Ee][Ss];MIDI_ENABLE = yes;g' {} +
```

* replace `# MIDI controls` with `# MIDI support`

Replace `# MIDI controls` with `# MIDI support` in keyboard-level `rules.mk` files.

Command:

```
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e 's;#[ \t]*MIDI[ \t]*\(controls\|support\).*;# MIDI support;g' {} +
```

* align inline comments

Aligns the inline comments to the length used by the QMK AVR rules.mk template.

Command:

```
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e 's;MIDI_ENABLE *= *yes.*;MIDI_ENABLE = yes           # MIDI support;g'  {} +
```

* remove commented instances of `MIDI_ENABLE` from keyboard `rules.mk` files

Commands:

```
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e 's;#\([ \t]*MIDI_ENABLE\) = yes; \1 = no ;' {} +
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e 's;^\([ \t]*\)\(MIDI_ENABLE = no\);\2\1;' {} +
find keyboards/ -type f -name 'rules.mk' -and -not -path '*/keymaps/*' -exec sed -i -e '/^[ #]\+MIDI_ENABLE *= *no/d' {} +
```

* remove MIDI configuration boilerplate from keyboard config.h files

Co-authored-by: Nick Brassel <nick@tzarc.org>