feat(shellcheck): add code actions to disable rule

Implements #933.

Always add a code action to disable a given diagnostic for a given line
or for the whole file.
This patch handles:
 * indentation
 * existing directive. It also sorts the disable directives if any
 * multi-line command

Add corresponding tests.

Signed-off-by: Thomas Faivre <thfaivre@gmail.com>

Author: ThomasFaivre

server/src/__tests__/server.test.ts

@@ -216,7 +216,7 @@ describe('server', () => {
         {} as any,
       )
 
-      expect(result).toHaveLength(1)
+      expect(result).toHaveLength(3)
       const codeAction = (result as CodeAction[])[0]
       expect(codeAction.diagnostics).toEqual([fixableDiagnostic])
       expect(codeAction.diagnostics).toEqual([fixableDiagnostic])

server/src/server.ts

@@ -398,7 +398,7 @@ export default class BashServer {
 
     const codeActions = params.context.diagnostics
       .map(({ data }) => codeActionsForUri[data?.id])
-      .filter((action): action is LSP.CodeAction => action != null)
+      .flat()
 
     logger.debug(`onCodeAction: found ${codeActions.length} code action(s)`)