Add support for Bicep when installed as a plugin to Azure CLI (#4496)

* Add support for Bicep when installed as a plugin to Azure CLI

The compiler for Microsoft's DSL Bicep can be installed both
independently and as a plugin to Azure CLI. The latter is probably how
most people install it.

The program output is the same but Azure CLI wraps the arguments and has
a slightly different interface, hence I opted to copy the old linter and
modify it to match the plugin arguments.

* Fix bicep/az_bicep tests, arguments and parsing

* Actually test the ale_linters#bicep#az_bicep#Handle function in the
  test that should test that function, not
  ale_linters#bicep#bicep#Handle.

* Use the same method as in bicep/bicep for discarding output file, i.e.
  by specifying --outfile to a null file.

* Fix parsing of occasionally occurring leading error type (such as
  'ERROR: ').

* Correct option defaults for bicep & az_bicep specified in documentation

test/handler/test_bicep_az_bicep_handler.vader

@@ -0,0 +1,41 @@
+Before:
+  runtime ale_linters/bicep/az_bicep.vim
+
+After:
+  Restore
+
+  call ale#linter#Reset()
+
+Execute(The az_bicep handler should handle basic warnings):
+  AssertEqual
+  \ [
+  \   {
+  \     'filename': '/tmp/nvimhxqs5D/1/dns.bicep',
+  \     'lnum': 7,
+  \     'col': 10,
+  \     'type': 'W',
+  \     'code': 'no-unused-existing-resources',
+  \     'text': 'Existing resource "asdasd" is declared but never used. [https://aka.ms/bicep/linter/no-unused-existing-resources]',
+  \   },
+  \   {
+  \     'filename': '/tmp/nvimhxqs5D/1/dns.bicep',
+  \     'lnum': 106,
+  \     'col': 6,
+  \     'type': 'E',
+  \     'code': 'BCP019',
+  \     'text': 'Expected a new line character at this location.',
+  \   },
+  \   {
+  \     'filename': '/tmp/cluster.bicep',
+  \     'lnum': 25,
+  \     'col': 30,
+  \     'type': 'E',
+  \     'code': 'BCP334',
+  \     'text': 'The provided value has no configured minimum length and may be too short to assign to a target with a configured minimum length of 1.',
+  \   },
+  \ ],
+  \ ale_linters#bicep#az_bicep#Handle(1, [
+  \   '/tmp/nvimhxqs5D/1/dns.bicep(7,10) : Warning no-unused-existing-resources: Existing resource "asdasd" is declared but never used. [https://aka.ms/bicep/linter/no-unused-existing-resources]',
+  \   '/tmp/nvimhxqs5D/1/dns.bicep(106,6) : Error BCP019: Expected a new line character at this location.',
+  \   'ERROR: /tmp/cluster.bicep(25,30) : Warning BCP334: The provided value has no configured minimum length and may be too short to assign to a target with a configured minimum length of 1.',
+  \ ])

test/handler/test_bicep_bicep_handler.vader

@@ -6,10 +6,11 @@ After:
 
   call ale#linter#Reset()
 
-Execute(The cmake_lint handler should handle basic warnings):
+Execute(The bicep handler should handle basic warnings):
   AssertEqual
   \ [
   \   {
+  \     'filename': '/tmp/nvimhxqs5D/1/dns.bicep',
   \     'lnum': 7,
   \     'col': 10,
   \     'type': 'W',
@@ -17,6 +18,7 @@ Execute(The cmake_lint handler should handle basic warnings):
   \     'text': 'Existing resource "asdasd" is declared but never used. [https://aka.ms/bicep/linter/no-unused-existing-resources]',
   \   },
   \   {
+  \     'filename': '/tmp/nvimhxqs5D/1/dns.bicep',
   \     'lnum': 106,
   \     'col': 6,
   \     'type': 'E',

test/linter/test_bicep_az_bicep.vader

@@ -0,0 +1,21 @@
+Before:
+  call ale#assert#SetUpLinterTest('bicep', 'az_bicep')
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The default command should be correct):
+  if has('win32')
+      AssertLinter 'az', ale#Escape('az') . ' bicep build --outfile NUL --file %s '
+  else
+      AssertLinter 'az', ale#Escape('az') . ' bicep build --outfile /dev/null --file %s '
+  endif
+
+Execute(The executable should be configurable):
+  let g:ale_bicep_az_bicep_executable = 'foobar'
+
+  if has('win32')
+      AssertLinter 'foobar', ale#Escape('foobar') . ' bicep build --outfile NUL --file %s '
+  else
+      AssertLinter 'foobar', ale#Escape('foobar') . ' bicep build --outfile /dev/null --file %s '
+  endif