feat(cli-repl): fix files as positional arguments and add --file MONGOSH-769 (#890)

- If the first positional argument ends in .mongodb or .js and is not a
  connection string, treat it as a filename.
- Add a `--file` (`-f`) flag for specifying filenames that avoids this
  ambiguity.
- Internally, avoid referring to positional arguments in general and
  be specific about whether the connection specifier or the filenames
  are being accessed
- As drive-by fixes, fix the spelling of `tlsAllowInvalidHostname` and
  drop the extra unnecessary `start` argument handling.

Author: addaleax

README.md

@@ -24,7 +24,7 @@ variable. For detailed instructions for each of our supported platforms, please
 
 ## CLI Usage
 ```shell
-  $ mongosh [options] [db address]
+  $ mongosh [options] [db address] [file names (ending in .js or .mongodb)]
 
   Options:
 

packages/cli-repl/README.md

@@ -6,7 +6,7 @@ CLI interface for [MongoDB Shell][mongosh], an extension to Node.js REPL with Mo
 
 ## Usage
 ```shell
-  $ mongosh [options] [db address]
+  $ mongosh [options] [db address] [file names (ending in .js or .mongodb)]
 
   Options:
 

packages/cli-repl/package.json

@@ -19,8 +19,7 @@
   },
   "scripts": {
     "compile-ts": "tsc -p tsconfig.json",
-    "start": "node bin/mongosh.js start",
-    "start-async": "node bin/mongosh.js start --async",
+    "start": "node bin/mongosh.js",
     "pretest": "npm run compile-ts",
     "test": "cross-env TS_NODE_PROJECT=../../config/tsconfig.test.json mocha -r \"../../scripts/import-expansions.js\" --timeout 60000 --colors -r ts-node/register \"./{src,test}/**/*.spec.ts\"",
     "test-ci": "cross-env TS_NODE_PROJECT=../../config/tsconfig.test.json mocha -r \"../../scripts/import-expansions.js\" --timeout 60000 -r ts-node/register \"./{src,test}/**/*.spec.ts\"",