.NET Interactive: Enable_try_dotnet_to_batch_8b

[v-mepa]

Enable_try_dotnet_to_batch_8b

URL	Comments
https://docs.microsoft.com/en-us/dotnet/api/system.char
https://docs.microsoft.com/en-us/dotnet/api/system.char.isnumber
https://docs.microsoft.com/en-us/dotnet/api/system.char.getnumericvalue
https://docs.microsoft.com/en-us/dotnet/api/system.char.equals
https://docs.microsoft.com/en-us/dotnet/api/system.char.parse
https://docs.microsoft.com/en-us/dotnet/api/system.char.convertfromutf32
https://docs.microsoft.com/en-us/dotnet/api/system.char.isletter	Duplicate samples for all overloads? Potentially move it to the MemberGroup

[v-mepa]

fyi @mairaw, I made updates to API'S without comments.
However this PR is showing 'branch_8a' updates also. I have added that API at the end with comment.

[mairaw]

Thank you @v-mepa. I just checked all the examples again and it seems two don't work on Interactive.

[mairaw]

Looks good. Thanks @v-mepa!