We were previously only looking at the `cellar` value when pouring
bottles and ignoring the `prefix` and (implicit) `repository`.

Actually look at these values and set the defaults for each platform.

Also, when we're relocating to create or pour bottles when `prefix`
and `repository` are equal then skip relocating the `repository` and
always use references to the `prefix` instead.

Fixes #9453

The first attempt to build and pull a formula (hello) for linux in homebrew-core
resulted in a wrong cellar line being added to the formula's bottle block.

How to test/debug this, using the 4 bottles that where built for hello:
brew bottle --merge --debug hello--2.10_1.mojave.bottle.json hello--2.10_1.x86_64_linux.bottle.json hello--2.10_1.big_sur.bottle.json hello--2.10_1.catalina.bottle.json

This command would add create the following bottle block:

  bottle do
    cellar "/home/linuxbrew/.linuxbrew/Cellar"
    sha256 "a0af7dcbb5c83f6f3f7ecd507c2d352c1a018f894d51ad241ce8492fa598010f" => :big_sur
    sha256 "5334dd344986e46b2aa4f0471cac7b0914bd7de7cb890a34415771788d03f2ac" => :catalina
    sha256 "22948764d8f8d7be4870ff92dae64d986eb63a9150b219c20fff87d1a6aa93d6" => :mojave
    sha256 "702dc7f78444d2f4f1c19324be654bcbb8b99dd0e9ce26c3e2fbc3b6464a189f" => :x86_64_linux
  end

After the change in this PR, the result is the following:

  bottle do
    sha256 "a0af7dcbb5c83f6f3f7ecd507c2d352c1a018f894d51ad241ce8492fa598010f" => :big_sur
    sha256 "5334dd344986e46b2aa4f0471cac7b0914bd7de7cb890a34415771788d03f2ac" => :catalina
    sha256 "22948764d8f8d7be4870ff92dae64d986eb63a9150b219c20fff87d1a6aa93d6" => :mojave
    sha256 "702dc7f78444d2f4f1c19324be654bcbb8b99dd0e9ce26c3e2fbc3b6464a189f" => :x86_64_linux
  end

The brew bottle --merge code will pick the most common cellar line between the 4 bottles, by order of priority:
- non-relocatable (fixed cellar path)
- cellar :any
- cellar :any_skip_relocation

In the case of the hello bottle, the 3 mac bottles are "cellar :any_skip_relocation", and the linux bottle
is non-relocatable. So the linux bottle wins and the code correctly determines that the 4 bottles should
be non-relocatable.

In that case, the /home/linuxbrew/.linuxbrew/Cellar path is defined as cellar, and by convention
we do not write that out to the formula file, hence the cellar path check that needs to be modified
in this PR.

This PR also fixes the same situation for mac ARM cellar paths

- Output `brew doctor` and `brew install` messages noting this configuration is (currently) unsupported and encourage use of Rosetta instead
- Output Rosetta 2 usage in `brew config` on ARM (whether in Rosetta 2 or not)
- Check the architecture of (newly installed) dependencies and ensure they are using the correct architecture.
- Don't allow installing macOS Intel Homebrew in macOS ARM Homebrew default prefix (and vice versa
- Actually write out the architecture of dependencies to the tab rather than generating and throwing them away
- Set and document the expected default prefix for macOS Intel Homebrew, macOS ARM Homebrew (`/opt/homebrew`) and Homebrew on Linux

While we're here:
- Don't say Big Sur is a prerelease version but still make it clear we
  don't support it (yet).
- Don't reference non-existent IRC channel

Co-authored-by: Mike McQuaid <mike@mikemcquaid.com>

Align the logic in `cleanup_portable_ruby` with that in `ruby.sh`.

Co-authored-by: Maxim Belkin <maxim.belkin@gmail.com>
Co-authored-by: Mike McQuaid <mike@mikemcquaid.com>

I was hoping that these would speed up boot but unfortunately they make
no difference. They are a bit more minimal anyway so probably a good
idea.

Fixes #5730

Refactor the CLI::Args module so it doesn't have different paths to
check arguments depending on whether the arguments have been parsed or
not. Instead, set the values we need from the global ARGV at
first, global initialisation time where they will be thrown away when
the actual arguments are parsed.

To do this some other general refactoring was needed:
- more methods made private when possible
- e.g. `HEAD?` used consistently instead of `head` before arguments
  are parsed.
- formula options are only parsed after named arguments are extracted

Our usage of `ARGV` will go away soon enough and maintaining state
between `ARGV` and `ARGV_WITHOUT_MONKEY_PATCHING` is futile.

Fixes #7397

Move some logic from `CLI::Parser` to `CLI::Args` to simplify and make
more consistent the initialisation process.

If we initialize it with OpenStruct, then methods defined in CLI::Args
cannot be called and they would always return nil leading to bugs

- This also required auto-fixes for Layout/EmptyLinesAroundBlockBody and
  Layout/InconsistentIndentation once the auto-fixer had got rid of the
  "redundant begin"s.

also use them to detect if prefix line in bottle block is needed

This means that any new environment variables or changes to `bin/brew`
or `brew.sh` will be used in the new process. This also allows the
removal of various fallbacks from autoupdates from old versions.

This serves a similar purpose to the HOMEBREW_FORCE_HOMEBREW_ORG
variable but applies to more settings.