Add Leo shortcut to URL bar microphone

[SergeyZhukovsky]

We want to open Leo's chat window with a text from dictation on URL bar microphone tap.
Let's make it for English locale only currently and detect if the phrase starts with Leo. For example:

1. Leo, what time is it now - opens a chat window with a prompt what time is it now.
2. Leo - brings up a chat window without anything filled in a prompt Edit box.

[hffvld]

Verified on Galaxy Tab S8 and Pixel 7 using version(s):

Device/OS: 
- Galaxy Tab S8 / gts8wifixx-user 14 UP1A.231005.007 release-keys
- Pixel 7 / panther_beta-user 15 AP31.240517.031 release-keys
Brave build: 1.68.101
Chromium: 126.0.6478.126 (Official Build) beta (64-bit) 

Filed follow-up issue #39534

STEPS:

1. Follow the STR/TP from Add Leo shortcut to URL bar microphone #38089 (comment)
2. Verify

ACTUAL RESULTS:

• Verified that the phrase Leo, what time is it now - opens a chat window with a prompt what time is it now
• Verified that the phrase Leo - brings up a chat window without anything filled in a prompt Edit box
• Verified that the phrase Hi Leo is not triggering Leo chat to be opened, even if the phrase contains Leo word

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Galaxy Tab S8

2024-07-02_11-59-47.mp4

Pixel 7

2024-07-02_10-55-42.mp4

2024-07-02_11-00-17.mp4

2024-07-02_11-18-52.mp4