llms/googleai: Support more `option.ClientOption` and update google ai sdk

[wangjiancn]

Support github.com/google/generative-ai-go/genai option.ClientOption:

• WithCredentialsJSON
• WithCredentialsFile
• WithHttpClient

Without WithCredentialsFile, vertex ai cannot run in non-GCP environments.

Fixe: #838

PR Checklist

• [x] Read the Contributing documentation.
• [x] Read the Code of conduct documentation.
• [x] Name your Pull Request title clearly, concisely, and prefixed with the name of the primarily affected package you changed according to Good commit messages (such as memory: add interfaces for X, Y or util: add whizzbang helpers).
• [x] Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• [x] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. Fixes #123).
• [x] Describes the source of new concepts.
• [x] References existing implementations as appropriate.
• [x] Contains test coverage for new functions.
• [x] Passes all golangci-lint checks.

[skrishnan-sap]

@wangjiancn Thank you for this PR. I was also adding WithHTTPClient option with #840 . I will close my PR, but would ask whether you would like to take over the unit test I added for the scenario from my PR?

[wangjiancn]

@wangjiancn Thank you for this PR. I was also adding WithHTTPClient option with #840 . I will close my PR, but would ask whether you would like to take over the unit test I added for the scenario from my PR?

Sure, I'll take a moment to incorporate the test case. I've just been handling the configuration, and I understand it should work without issues.

[wangjiancn]

@skrishnan-sap

    github.com/tmc/langchaingo v0.1.10 => github.com/wangjiancn/langchaingo v0.1.11-dev3

[xavidop]

looking forward to this PR!

[tmc]

@wangjiancn would love to see this get over the line!

[wangjiancn]

@tmc I've updated the PR, could you please review it? The related code has been used in the production environment, so please help to merge it first.

[eliben]

Just a quick note: I'll be happy to review this PR, but am on vacation now and will be back in about a week. Hopefully it can wait until then

[xavidop]

It looks good to me!