enforce project id generation (which requires a repo to exists)

[samuelstroschein]

#2013 opens the possibility to enforce project ids and get rid of conditional logic and bugs like https://github.com/opral/monorepo/issues/2070

Task

Make project.id not potentially undefined

https://github.com/opral/monorepo/blob/27b1307868aaf6baf68fe4f6c7cb058f7931dbd1/inlang/source-code/sdk/src/api.ts#L40-L42

[jldec]

see https://github.com/opral/monorepo/issues/2101#issuecomment-1911907633 waiting for definitive way to ensure that projects have a project id. - #2063