Leo - Simplify AI model intro and add tooltip for more details

[aguscruiz]

Description

We're simplyfing the model introduction for each new conversation. This includes:

• Only visible content at the initial state will be the Model type (Chat) / Model name / Model creator / Info icon
• When you click/tap the info button, users get a tooltip with the model description.
• There's a new piece of content that indicates if the model is hosted by Brave or not.
• We include a "Learn more" link in case we want to link users to more info.

https://www.figma.com/file/m0Gdbf0wtqyfEFGm32VLLc/Leo?type=design&node-id=3096%3A80072&mode=design&t=WqIHp5r9TFoBBBtg-1

Actual result:

Expected result:

[stephendonner]

Verification PASSED using

Brave | 1.67.76 Chromium: 125.0.6422.26 (Official Build) nightly (64-bit)
-- | --
Revision | c8696983cac61f6c5a22bc23ca991c20737fd0b0
OS | Windows 10 Version 22H2 (Build 19045.4355)

Shared Steps:

1. installed `1.67.76` 2. launched Brave 3. opened a new-tab page 4. clicked on `Leo` in the sidebar 5. hovered over the `(i)` icon for each model 6. if available, also noted and clicked `Learn more` link

Confirmed model-intro, heading, and tooltip changes

Non-Premium (default) - PASSED

`Mixtral`:  `Claude Instant`:  `Claude 3 Haiku`:  `Llama 2 13b`: 

Premium - PASSED

### Confirmed `PREMIUM` light-blue/blurple badge `Claude 3 Sonnet`: 

Hover on tooltip - PASSED*

Confirmed the `Learn more` link goes to `https://support.brave.com/hc/en-us/categories/20990938292237-Brave-Leo` 

*Logged:

• https://github.com/brave/brave-browser/issues/38171

Encountered:

• https://github.com/brave/brave-browser/issues/38157

[Uni-verse]

Verified on Samsung Galaxy S21 using version:

Brave   1.67.92 Chromium: 125.0.6422.76 (Official Build) beta (64-bit) 
Revision    d751d2edf40b466560aaeecc4c4919041f41c20d
OS  Android 13; Build/TP1A.220624.014; 33; REL

New Onboarding (NTP)

• Ensured graphics are removed from the onboarding and theme matches the figma specs.
• Ensured user is able to complete onboarding when summarizing with Leo.

Example	Example	Example

New Onboarding (Webpage)

• Ensured graphics are removed from the onboarding and theme matches the figma specs.
• Ensured context switch is displayed and disabling switching will remove the summarize block.
• Ensured user is able to complete onboarding when summarizing with Leo.

Example	Example	Example	Example	Example

Tool Tip

• Ensured tool tip is shown beside the model name.
• Ensured that tapping on tool tip icon will display the dialog.
• Ensured tapping on Learn more will launch the support page.
• Ensured tapping anywhere in chat will dismiss the tool tip.
• Ensured tool tip displays correctly for each of the models.
• Ensured tool tip is displayed ok in both orientations.

Mixtral	Claude Instant	Haiku	Sonnet	Llama	Support page