Implement Homebrew as the system deployer for macOS. (#1185)

Implement Homebrew as the system deployer for macOS. (#1185)

* Implement Homebrew as the system deployer for macOS.

  * src/alire/alire-origins-deployers-system-homebrew.adb: new.
  * src/alire/alire-origins-deployers-system-homebrew.ads: new.
  * src/alire/alire-origins-deployers-system.adb (Platform_Deployer):
      When the platform distro manager is Homebrew, return Homebrew.Deployer.
  * src/alire/alire-platforms.ads (Distributions): include macOS.
    (Package_Managers): add Homebrew.
    (Distro_Manager): for macOS, use Homebrew.
  * src/alire/alire-utils-tools.adb (System_Package_For_Tool): treat MacOS
      like other distributions.
  * src/alire/os_macos/alire-platforms-current__macos.adb
    (Detected_Distribution): return Platforms.MacOS.
  * testsuite/drivers/helpers.py (on_macos()): new.
    (distribution()): return 'MACOS' if on_macos() is True.

; Squashed commit of the following:

; commit 0110299ceb66f58cd4793fd78a69fc5b100b4ccf
; Author: Simon Wright <simon@pushface.org>
; Date:   Fri Sep 9 17:45:04 2022 +0100

;     Restore test to correct sense.

; commit d396b6b54a73bbbfd59071539bf6268bccce3cf0
; Author: Simon Wright <simon@pushface.org>
; Date:   Fri Sep 9 17:34:54 2022 +0100

;     Replace assertions in Homebrew deployer with exceptions

; commit d7603110b9543bdaac9516fa844599e87fac70aa
; Author: Simon Wright <simon@pushface.org>
; Date:   Mon Sep 5 14:14:03 2022 +0100

;     Recognise macOS as a distribution.

;       * testsuite/drivers/helpers.py (on_macos()): new.
;         (distribution()): check on_macos(). Return 'MACOS' if true.

; commit 8703acfeb8fdf336d862cefc16706eac5d3f0758
; Author: Simon Wright <simon@pushface.org>
; Date:   Sun Sep 4 17:33:13 2022 +0100

;     Use 'brew info' to get available, installed versions.

; commit 8b22b904e19d64fecb89233e6527c2faf655d982
; Author: Simon Wright <simon@pushface.org>
; Date:   Wed Aug 31 15:54:51 2022 +0100

;     Continuing.

; commit a9821ed9a605e30b5699a49df6fffd11224ab931
; Author: Simon Wright <simon@pushface.org>
; Date:   Mon Aug 22 17:09:48 2022 +0100

;     First changes for macOS Homebrew.

* Implement Homebrew for MacOS: response to comments on PR#1185

  * .github/workflows/ci-macos.yml (Run test script): renamed to
      "Run test script (without Homebrew)".
    (Run test script (with Homebrew)): added 'eval $(brew shellenv)' before
      running the test script, so that HOMEBREW_PREFIX gets defined.
  * src/alire/alire-origins-deployers-system-homebrew.adb
    (Homebrew_Prefix, Homebrew_Present): removed.
    (Get_Info): named the declare block. Removed commented-out exception
      handler.
    (Already_Installed): use Get_Info's returned Installed_Version's length
      to determine the result.
    (Detect): Get_Version_From_String uses Semantic_Versioning.Parse.
        Don't check for Homebrew_Present, it has to be or we wouldn't be
        called.
  * src/alire/alire-platforms.ads (Distributions): rename MacOS to Homebrew.
    (Distro_Manager): likewise.
  * src/alire/alire-utils-tools.adb (System_Package_For_Tool): MacOS (in
      'case Distribution)' changed to Homebrew.
  * src/alire/os_macos/alire-platforms-current__macos.adb
    (Homebrew_Prefix): new, gets the environment variable "HOMEBREW_PREFIX".
    (Homebrew_Present): new, true if the environment variable is present.
    (Detected_Distribution): checks Homebrew_Present, returns Homebrew
      or Distro_Unknown accordingly.
    (Distribution_Root): returns Homebrew_Prefix if present, otherwise "/".
  * testsuite/drivers/helpers.py (distribution()): if on macOS, return
      HOMEBREW if HOMEBREW_PREFIX is found, DISTRO_UNKNOWN otherwise.

* Remove improper pragma in response to comment on #1185

  * src/alire/alire-origins-deployers-system-homebrew.adb: removed
      the innefective pragma Warnings (Off).

* Merging with openSUSE changes in #1173.

  * src/alire/alire-origins-deployers-system.adb: added Homebrew option.
  * src/alire/alire-platforms.ads: likewise.
  * src/alire/alire-utils-tools.adb: likewise.

Co-authored-by: John Serock <1468970+serock@users.noreply.github.com>
Co-authored-by: GHA <actions@github.com>