Adds multiple choice message handling to MesopUI

[davorrunje]

Description

Remember all chats, and make them available to the user, so that she can revisit them.

In this first iteration:

chats are not persisted - when server goes down, they go as well
only completed chats can be saved
chats can not be resumed

Fixes #143

Type of change

Please delete options that are not relevant.

• New feature (a non-breaking change that adds functionality)

Checklist

• My code adheres to the style guidelines of this project (scripts/lint.sh shows no errors)
• I have conducted a self-review of my own code
• I have made the necessary changes to the documentation
• My changes do not generate any new warnings
• I have added tests to validate the effectiveness of my fix or the functionality of my new feature
• Both new and existing unit tests pass successfully on my local environment by running scripts/test-cov.sh
• I have ensured that static analysis tests are passing by running scripts/static-anaylysis.sh
• I have included code examples to illustrate the modifications

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 128 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
fastagency/ui/mesop/message.py	0.00%	68 Missing ⚠️
.../user_guide/custom_user_interactions/main_mesop.py	0.00%	32 Missing ⚠️
...cs_src/user_guide/external_rest_apis/main_mesop.py	0.00%	13 Missing ⚠️
fastagency/ui/mesop/data_model.py	0.00%	7 Missing ⚠️
fastagency/ui/mesop/components/inputs.py	0.00%	4 Missing ⚠️
...cs_src/user_guide/custom_user_interactions/main.py	0.00%	2 Missing ⚠️
fastagency/ui/mesop/main.py	0.00%	1 Missing ⚠️
fastagency/ui/mesop/send_prompt.py	0.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
fastagency/studio/models/agents/assistant.py	83.33% <ø> (ø)
fastagency/ui/mesop/base.py	0.00% <ø> (ø)
fastagency/ui/mesop/main.py	0.00% <0.00%> (ø)
fastagency/ui/mesop/send_prompt.py	0.00% <0.00%> (ø)
...cs_src/user_guide/custom_user_interactions/main.py	0.00% <0.00%> (ø)
fastagency/ui/mesop/components/inputs.py	0.00% <0.00%> (ø)
fastagency/ui/mesop/data_model.py	0.00% <0.00%> (ø)
...cs_src/user_guide/external_rest_apis/main_mesop.py	0.00% <0.00%> (ø)
.../user_guide/custom_user_interactions/main_mesop.py	0.00% <0.00%> (ø)
fastagency/ui/mesop/message.py	0.00% <0.00%> (ø)