Improvements to environment template

[glopesdev]

This PR introduces two quality of life improvements to the environment template experience:

• The bootstrapper will now always run at the .ps1 script location so it can be called safely with relative paths
• A default name of .bonsai is assigned to the template

This means it is now possible to simply call dotnet new bonsaienv to initialize a new default environment. The changes also allow independently controlling created folder name and environment folder name.

For example the following command will create a new folder project1 containing a bonsai environment folder named env.

dotnet new bonsaienv -o project1 -n .env