Recommend holding until after #13125 is fully digested and possibly until 0.96.

Description

Fixes one of the issues described in #13125

The do signature included a SyntaxShape:Any as one of the possible first-positional types. This is incorrect. do only takes a closure as a positional. This had the result of:

1. Moving what should have been a parser error to evaluation-time

   Before

   > do 1
   Error: nu::shell::cant_convert
   
     × Can't convert to Closure.
      ╭─[entry #26:1:4]
    1 │ do 1
      ·    ┬
      ·    ╰── can't convert int to Closure
      ╰────

   After

   > do 1
   Error: nu::parser::parse_mismatch
   
     × Parse mismatch during operation.
      ╭─[entry #5:1:4]
    1 │ do 1
      ·    ┬
      ·    ╰── expected block, closure or record
      ╰────

2. Masking a bad test in std assert

This is a bit convoluted, but std assert tests included testing assert error to make sure it:

• Asserts on bad code
• Doesn't assert on good code

The good-code test was broken, and was essentially bad-code (really bad-code) that wasn't getting caught due to the bad signature.

Fixing this resulted in parse time failures on every call to test_asserts (not something that particular test was designed to handle.

This PR also fixes the test case to properly evaluate std assert error against a good code path.

User-Facing Changes

• Error-type returned (possible breaking change?)

Tests + Formatting

• 🟢 toolkit fmt
• 🟢 toolkit clippy
• 🟢 toolkit test
• 🟢 toolkit test stdlib

After Submitting

N/A