/datapack create doesn't allow directory names with spaces or uppercase letters

The bug

The /datapack create command is incorrectly validating names of data packs. Data pack names should be allowed to contain both uppercase and lowercase letters, as well as spaces, since they are essentially directory names. The current behavior seems to follow the same rule as namespaces, only allowing a-z, 0-9, _, - and ., causing inconvenience for data pack makers.

Steps to Reproduce

1. Create a new world with Allow Commands enabled

2. Run

   /datapack create "Test" "test description"

   ❌ The command fails

3. Run

   /datapack create "test" "test description"

   ✔ The data pack is created successfully

4. Run

   /datapack create "test pack" "test description"

   ❌ The command fails

5. Run

   /datapack create "test_pack" "test description"

   ✔ The data pack is created successfully

Expected Result

Since the data pack names above are valid, all the commands should execute successfully.