feat(mcp): add --mcp-config-paths CLI argument

[floralph]

Summary

Add support for specifying additional MCP configuration files via the --mcp-config-paths CLI argument, enabling users to organize and share MCP server configurations across multiple projects and environments.

Description of changes

1. New CLI argument: Add --mcp-config-paths argument to specify additional MCP configuration files
2. Cross-platform support: Use OS-specific path separators (: on Unix/Mac, ; on Windows) for multiple paths
3. Configuration precedence: Implement clear precedence order: global < workspace < additional paths (left to right)
4. Path handling: Support tilde expansion (~/config.json) and relative paths in additional config paths
5. Error handling: Provide clear warnings for configuration conflicts and missing files
6. Comprehensive testing: Add extensive tests covering path parsing, precedence rules, and error scenarios

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[brandonskiser]

Note that we are currently making some changes w/ how MCP configuration will be handled, so not sure if we want to include this as a new feature if it'll be immediately replaced with another modality.

@chaynabors @mschrage what do you think?

[dingfeli]

Hi! We have moved the development of q chat back to our original repo: https://github.com/aws/amazon-q-developer-cli. Please rebase your branch onto our original repo. You can do so via the following:

With github cli:
Install gh cli if you haven't already:

brew install gh 

And run the following:

BRANCH=your-feature-branch-name
gh repo fork aws/amazon-q-developer-cli 
cd amazon-q-developer-cli git remote add autocomplete https://github.com/aws/amazon-q-developer-cli-autocomplete
git fetch amazon-q-developer-cli-autocomplete $BRANCH
git push origin $BRANCH

Or if you would like to do this without install the github cli:

1. Add amazon-q-developer-cli-autocomplete as remote for amazon-q-developer-cli

cd /path/to/your/fork/of/amazon-q-developer-cli

git remote add amazon-q-developer-cli-autocomplete url/to/your/fork/of/amazon-q-developer-cli-autocomplete

2. Fetch your feature branch from amazon-q-developer-cli-autocomplete

git fetch amazon-q-developer-cli-autocomplete your-feature-branch-name

3. Remake your PR

git push origin-to-your-fork your-feature-branch-name

brew install github
github repo fork amazon-q-developer-cli

Thank you for your contribution!
If you need any help, please reach out to @dingfeli.

[dingfeli]

In addition to the moving message, we have also just recently overhauled the chat config with agent: aws/amazon-q-developer-cli#2222, which overlaps with the goal of this PR.