build: remove unnecessary stability check (#23176)

Previously, it was necessary to attach on of the three "stability"
jsdoc tags (`@stable`, `@deprecated` or `@experimental`) to each
public API export.

To ensure that the public API was correctly tagged, the `ts-api-guardian`
would check that one of these tags appeared on every public export.

Now the doc-gen is able to compute that a code item is stable if
it does not contain the `@experimental` nor `@deprecated` tags.

Therefore there is no need to provide the `@stable` tag any more; and
this tag has now been marked as deprecated - i.e. it should not be used.

The ts-api-guardian has been modified in this commit so that it no longer
warns/fails if the `@stable` is missing.

PR Close #23176

tools/ts-api-guardian/lib/cli.ts

@@ -24,14 +24,8 @@ export function startCli() {
   const options: SerializationOptions = {
     stripExportPattern: argv['stripExportPattern'],
     allowModuleIdentifiers: [].concat(argv['allowModuleIdentifiers']),
-    onStabilityMissing: argv['onStabilityMissing'] || 'none'
   };
 
-  if (['warn', 'error', 'none'].indexOf(options.onStabilityMissing as string) < 0) {
-    throw new Error(
-        'Argument for "--onStabilityMissing" option must be one of: "warn", "error", "none"');
-  }
-
   for (const error of errors) {
     console.warn(error);
   }
@@ -85,7 +79,7 @@ export function parseArguments(input: string[]):
   const argv = minimist(input, {
     string: [
       'out', 'outDir', 'verify', 'verifyDir', 'rootDir', 'stripExportPattern',
-      'allowModuleIdentifiers', 'onStabilityMissing'
+      'allowModuleIdentifiers'
     ],
     boolean: [
       'help',
@@ -161,10 +155,7 @@ Options:
 
         --stripExportPattern <regexp>   Do not output exports matching the pattern
         --allowModuleIdentifiers <identifier>
-                                        Whitelist identifier for "* as foo" imports
-        --onStabilityMissing <warn|error|none>
-                                        Warn or error if an export has no stability
-                                        annotation`);
+                                        Whitelist identifier for "* as foo" imports`);
   process.exit(error ? 1 : 0);
 }