Create nu_glob::is_glob function (#14717)

# Description

Adds an `is_glob` function to the nu-glob crate that takes a string
pattern and returns whether or not it's a glob that would be expanded by
nu-glob. Right now, this just means checking if it contains `*`, `?`, or
`[`.

Previously, this same code was duplicated in the following places:
- `ls`: Determining whether to read a folder's contents or expand a glob
- `run_external.rs` in nu-command: Arguments to externals only have
n-dots and tilde expansion applied if they weren't globs
- `glob_from` in nu-engine:
  - `glob_from` can get the prefix in a simpler way for non-globs
- If the canonical path for a non-glob path contains glob
metacharacters, it needs to be escaped
- `completion_common.rs` in nu-cli: File/folder completions containing
glob metacharacters need to be wrapped in quotes

All of these locations can use `nu_glob::is_glob` now instead of rolling
their own checks. This does mean that nu-cli now has a dependency on
nu-glob.

# User-Facing Changes

Users of nu-glob will now be able to check if a given pattern is a glob
expanded by nu-glob.

For users of Nushell, completion suggestions for files containing `]`
will no longer be wrapped in quotes if they contain no other glob
metacharacters. This is because unmatched `]`s are ignored by nu-glob,
but we used to consider such file completions contaminated anyway.

# Tests + Formatting

This is a very basic function, so I just added some doctests.

# After Submitting

This is meant to be used in
https://github.com/nushell/nushell/pull/14674.

crates/nu-cli/src/completions/completion_common.rs

@@ -286,8 +286,7 @@ pub fn complete_item(
 // Fix files or folders with quotes or hashes
 pub fn escape_path(path: String, dir: bool) -> String {
     // make glob pattern have the highest priority.
-    let glob_contaminated = path.contains(['[', '*', ']', '?']);
-    if glob_contaminated {
+    if nu_glob::is_glob(path.as_str()) {
         return if path.contains('\'') {
             // decide to use double quote, also need to escape `"` in path
             // or else users can't do anything with completed path either.