feat(size/M):UI improvements and fixes.

[sachin-bruno]

• Send button text should be black
• Playground request/response pane dragbar thickness is high
• Need a little more padding above the request and response pane tabs and below the request url bar.
• Request name font size is too small - above request url
• Environments secrets right side playground - If no value for secret, make it editable by default
• In env > secret table > Value column alignment
• Unable to scroll inside code editor of new version while able to do the same in the old version.
• Configure environment tooltip for settings icon.