For # to start a comment, then it either need to be the first chara… (#14562)

This PR should close
1. #10327 
1. #13667 
1. #13810 
1. #14129 

# Description
For `#` to start a comment, then it either need to be the first
character of the token or prefixed with ` ` (space).

So now you can do this:
``` 
~/Projects/nushell> 1..10 | each {echo test#testing }                                                                                                                     12/05/2024 05:37:19 PM
╭───┬──────────────╮
│ 0 │ test#testing │
│ 1 │ test#testing │
│ 2 │ test#testing │
│ 3 │ test#testing │
│ 4 │ test#testing │
│ 5 │ test#testing │
│ 6 │ test#testing │
│ 7 │ test#testing │
│ 8 │ test#testing │
│ 9 │ test#testing │
╰───┴──────────────╯
```  

# User-Facing Changes
It is a breaking change if anyone expected comments to start in the
middle of a string without any prefixing ` ` (space).

# Tests + Formatting
Did all: 
- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use toolkit.nu; toolkit test stdlib"` to run the
tests for the standard library

# After Submitting
I cant see that I need to update anything in [the
documentation](https://github.com/nushell/nushell.github.io) but please
point me in the direction if there is anything.

tests/repl/test_parser.rs

@@ -169,6 +169,41 @@ fn comment_skipping_in_pipeline_3() -> TestResult {
     )
 }
 
+#[test]
+fn still_string_if_hashtag_is_middle_of_string() -> TestResult {
+    run_test(r#"echo test#testing"#, "test#testing")
+}
+
+#[test]
+fn non_comment_hashtag_in_comment_does_not_stop_comment() -> TestResult {
+    run_test(r#"# command_bar_text: { fg: '#C4C9C6' },"#, "")
+}
+
+#[test]
+fn non_comment_hashtag_in_comment_does_not_stop_comment_in_block() -> TestResult {
+    run_test(
+        r#"{
+        explore: {
+            # command_bar_text: { fg: '#C4C9C6' },
+        }
+    } | get explore | is-empty"#,
+        "true",
+    )
+}
+
+#[test]
+fn still_string_if_hashtag_is_middle_of_string_inside_each() -> TestResult {
+    run_test(
+        r#"1..1 | each {echo test#testing } | get 0"#,
+        "test#testing",
+    )
+}
+
+#[test]
+fn still_string_if_hashtag_is_middle_of_string_inside_each_also_with_dot() -> TestResult {
+    run_test(r#"1..1 | each {echo '.#testing' } | get 0"#, ".#testing")
+}
+
 #[test]
 fn bad_var_name() -> TestResult {
     fail_test(r#"let $"foo bar" = 4"#, "can't contain")
@@ -282,6 +317,11 @@ fn raw_string_with_equals() -> TestResult {
     )
 }
 
+#[test]
+fn raw_string_with_hashtag() -> TestResult {
+    run_test(r#"r##' one # two '##"#, "one # two")
+}
+
 #[test]
 fn list_quotes_with_equals() -> TestResult {
     run_test(