x/pkgsite: create GetModuleInfo function

[julieqiu]

As part of the new data model migration (#39629), we will need a function return the ModuleInfo for a given module_path and version.

This function will eventually replace the existing LegacyGetModuleInfo function.

The function signature will be:

GetModuleInfo(ctx context.Context, modulePath string, resolvedVersion string) (_ *internal.ModuleInfo, err error)

The function will execute the query below:

SELECT
    module_path,
    version,
    commit_time,
    version_type,
    source_info,
    redistributable,
    has_go_mod
FROM
    modules
WHERE
    module_path=$1
    AND version=$2;

Unlike LegacyGetModuleInfo, it is expected that the version passed into the function will always be a semantic version (i.e. GetModuleInfo will NOT need to handle the case where resolvedVersion == internal.LatestVersion).

[namaggarwal]

Hello @julieqiu, Can I pick this up ?

[julieqiu]

Yes, please do!

[gopherbot]

Change https://golang.org/cl/241038 mentions this issue: internal/postgres: add GetModuleInfo function