DOC-5601 Transform functions

[aimurphy]

Move transform functions content from streaming-learning-docs to astra-streaming-docs and pulsar-docs:

• Added transform function reference page (same as the astra one because almost all of the content is from docs-common).
• Added steps to deploy transform functions to the main functions page

[plpesvc-ds]

Build successful! ✅
Pull requests with matching branch name doc-5601 included in the build:

• DOC-5601 Transform functions #184 (this pull request)
• https://github.com/riptano/docs-common/pull/263
• DOC-5601 Remove functions topics datastax-archive/streaming-learning-docs#71
• DOC-5601 Transform functions astra-streaming-docs#163

Deploying draft.
Deploy successful! View draft

[mendonk]

LGTM