[UI] Filter logs with regex

### Proposal
Add to the logs page (stdout , stderr) of a task an option to set a regex that will filter lines . Something like `grep`.

### Use-cases
Quickly follow logs, filtering unwanted lines and keeping only what is useful.

### Attempted Solutions
CLI is the alternative

Start at the Nomad UI logs page and trace how task stdout and stderr are displayed. Compare the requested behavior with the existing CLI log filtering, then define how regex input, matching lines, and invalid expressions should behave before identifying the relevant UI tests or adding coverage.

Written by the indexing model from the issue text.