Make runtimeconfig.dev.json configProperties take precedence over runtimeconfig.json

[Copilot]

configProperties set in .runtimeconfig.json currently overwrite values from .runtimeconfig.dev.json, preventing dev-only overrides. This makes them not actually useful in a dev scenario.

Technically a breaking change and we will file it as such, but it should be very low-impact. The SDK has disabled emitting runtimeconfig.dev.json by default since .NET 6 and it was never used for properties.

[Copilot]

Pull request overview

This PR changes host runtime configuration parsing so configProperties specified in *.runtimeconfig.dev.json are not overwritten by the same property name in *.runtimeconfig.json (dev config wins for configProperties only). It updates HostActivation tests to validate the new precedence.

Changes:

• Update runtime_config_t::parse_opts to skip assigning a configProperties entry if that key already exists in m_properties.
• Update the related HostActivation test to assert dev-config precedence.

Show a summary per file

File	Description
src/native/corehost/runtime_config.cpp	Implements “first value wins” for configProperties by skipping overwrites when a key is already present (dev config parsed first).
src/installer/tests/HostActivation.Tests/RuntimeProperties.cs	Renames/updates a test to assert .runtimeconfig.dev.json overrides .runtimeconfig.json for the same property name.

Copilot's findings

Comments suppressed due to low confidence (1)

src/native/corehost/runtime_config.cpp:103

• This adds an extra hash lookup and string conversion per property (count + later operator[] assignment), and the brace-less if is inconsistent with the surrounding style in this function. Consider using a single lookup/insert pattern (and braces) so existing entries are skipped without paying for two lookups.

        for (const auto& property : properties_obj)
        {
            if (m_properties.count(property.name.GetString()) != 0)
                continue;

            if (property.value.IsString())
            {
                m_properties[property.name.GetString()] = property.value.GetString();
            }

• Files reviewed: 2/2 changed files
• Comments generated: 1

[Copilot]

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1