Python: Unsafe input handling

[eavanvalkenburg]

Motivation and Context

Implements dealing with unsafe content, by doing HTML parsing on variables and function results.

Closes: #5889

Description

Adds parameter allow_dangerously_set_content to:

• InputVariable
• PromptTemplateConfig
• PromptTemplateBase

The behavior is that if the flag is set to True on the template itself (KernelPromptTemplate, Jinja2PromptTemplate or HandlebarsPromptTemplate) the behavior is the same, no encoding is done on inputs.

Otherwise:

• variables are encoded by default, this can be switched off using the InputVariables class for that variable.
• function output is encoded by default, this can be switched off using the flag in the PromptTemplateConfig, this is not yet possible to do on a per function basis.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[markwallace-microsoft]

Python 3.10 Test Coverage Report •

File	Stmts	Miss	Cover	Missing
semantic_kernel
kernel.py	314	57	82%	123, 125, 183–186, 188–192, 194–197, 204, 211–220, 257–260, 270–275, 280, 284–287, 380–416, 535–536, 763, 784–786, 822, 824, 834
semantic_kernel/contents
streaming_chat_message_content.py	84	2	98%	193–194
text_content.py	22	2	91%	40, 47
semantic_kernel/functions
kernel_function.py	73	2	97%	142, 161
kernel_function_from_prompt.py	163	5	97%	171, 197, 294, 310, 364
semantic_kernel/planners/sequential_planner
sequential_planner.py	65	6	91%	69, 73, 104, 120, 129–130
semantic_kernel/prompt_template
jinja2_prompt_template.py	44	3	93%	62–64
kernel_prompt_template.py	85	3	96%	119–121
prompt_template_config.py	51	6	88%	39, 47, 68, 73–74, 82
semantic_kernel/prompt_template/utils
handlebars_system_helpers.py	93	3	97%	16, 43–44
jinja2_system_helpers.py	48	3	94%	15, 45, 50
semantic_kernel/template_engine/blocks
code_block.py	70	1	99%	130
TOTAL	6089	1061	83%

Python 3.10 Unit Test Overview

Tests	Skipped	Failures	Errors	Time
1278	1 💤	0 ❌	0 🔥	14.816s ⏱️